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XtremeRevolution's Subwoofer Boxes

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XtremeRevolution's Subwoofer Boxes

This thread will be dedicated to the design and sale of my custom subwoofer boxes and baffles. I've decided to make my services available to the community at an affordable price, as custom, well-built sub boxes are generally not cheap, and pre-fabricated boxes are generally junk.

If you need a subwoofer box designed and can build your own, if you have a box and want to see how a sub will sound inside it, or if you need a box designed and built by me, you've come to the right place.

Subwoofer Box Design

I offer my services for subwoofer box design free of charge. If you need a subwoofer box designed for a sub you own or will be purchasing to put in your Cruze, please reply to this thread and provide me with the following information:

1. Make/Model of Subwoofer
2. Subwoofer's T/S parameters (Qes, Qms, Fs, Vas, Sd, Xmax, and RMS Power handling)
3. Where in the trunk you plan on placing this sub
4. Make and model of your subwoofer amplifier
5. Types of music you primarily listen to
6. Primary goal for performance (Sound quality, SPL, best use of a box you already own, smallest box possible, etc.)

Based on the above information, I will provide you with a frequency response chart of a simulation for a given sub, in a specific box, with your car's cabin pressurization gain and boundary loading (cabin transfer function) to give you an idea of what it will sound like in your car.

Subwoofer Box Sales
While I'd prefer to teach you how to build a good box, I understand that not everyone has access to the tools or space to build one, so I also offer my services for building a sub box for you should you need one built.

Pricing:
Single 10"-12": $195
Dual 10"-12": $235


The above pricing is for subs that require .75-1.25 cubic feet of internal volume per sub, sealed. I can provide you with a price for boxes that don't meet those dimensions or for 8" or 15" subwoofers on a case by case basis. Ported boxes will also be quoted on a case by case basis.

These boxes will be built with routed bracing and an extra thick front baffle with a recess for the sub. These will be made out of 3/4" MDF, will be precision cut and routed, free of leaks, and will be nearly indestructible. Basically, the MDF material will fail before the joints do. They will be carpeted with your choice of either Black, Charcoal, or Medium Gray carpeting. I can substitute that for a different fabric (such as black shag, faux tiger fur, etc.) for an additional cost. A strip of speaker gasket tape and an adequate length of 12 gauge OFC wire will be included.

Prices include mineral wool as fill. Depending on where you live, expect shipping to be anywhere from $40-$80. Particularly large boxes may be more expensive, while particularly small ones may be less expensive. With double thick baffles and internal bracing, these boxes typically weigh 35-60lbs unloaded. As always, local pick-up is free. I am located in the southwest Chicago suburbs.

I was recently asked why the prices of my boxes was so high. I figured I'd copy my response here so people could get an idea of what's involved.

  • I use quality materials. I use 3/4" MDF instead of 5/8" like some companies do. I use latex backed cabinet fabric so it doesn't shed, I use a gold plated terminal, and 3M Super 77 spray adhesive to hold the cabinet fabric on so it doesn't peel off like I've seen happen on countless prefabbed boxes.
  • I glue my boxes together with Titebond II wood glue. This might sound like a no-brainer, but if you actually take apart a pre-fabbed box, you'll find that they aren't actually glued. They are nailed or screwed together, and they are caulked on the inside. The caulk breaks apart after a little while and the box leaks everywhere. Gluing takes far more time. My boxes don't need caulk because the glue seals it perfectly. In fact, once clamped and dried, the bond is so strong that if you try to break apart two glued pieces of MDF, the MDF breaks before the glue joint does. In other words, short of severe water damage, my boxes are indestructible, and that's a difference you can hear. My sub boxes make subs sound louder and tighter than any cheap prefabbed box you can pull off a shelf (assuming same alignment).
  • Design. I design them for free, but you won't find anyone else making 4-point bracing like this at anywhere near this price. A double thick baffle with a precision flush mount made specifically for the sub you're using? You will have a hard time finding any shop that can do this well, let alone at an affordable rate. My boxes are also designed to fit in the specific car while taking up as small of a footprint as possible.
  • Custom work. Let's face it, I can't work for free, and I charge a heck of a lot less than a good retail shop will. You'll find prices in the $200-$500 range. For a single sub box, here are my rounded costs. $35 on MDF, $15 on cabinet fabric, $5 for the terminal, $10 for the spray adhesive, $5 for the wall damping, and figure in another $5 for things like crown staples, screws, and speaker gasket tape. Total is around $75, and I still have to put miles on my car and spend gas going to Home Depot or Menard's to pick up materials from time to time. I'm sure some of you have seen boxes for sale online, shipped to your door for that much as it costs me to make mine, but my boxes aren't made in China; they're made in my wood shop, which brings me to my next reason:
  • My carbide router bits and saw blades aren't cheap and MDF wears them out much faster than real wood. Shop vac filters aren't free. My circular saw was $200, my router was $300, my shop vac was $100, my router bits were another $200, my sliding miter saw was $350, my air compressor was $250, my crown stapler was $50, my brad nailer was $150, my drill was $200, and the list goes on and on and on. All in all, I have well over $2500 invested in tools, all of which wear down over time, and we aren't even getting into the cost of electricity to power them.
  • It takes me 5-7 hours to make a box, depending on number of subs and complexity, and that doesn't include cleanup time or tool maintenance.
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Discussion Starter · #5 ·
Good luck in your entrepreneurship.
Eh, I'm not really doing it to make a business out of it. I use my home theater speaker design for that. This is more something I'm trying to do for the community. A good custom box will run you about $400-$800 from a high end shop, and that's what I build.
 

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Discussion Starter · #8 · (Edited)
Can we get together some weekend and build one? I'll supply the stuff and a case of your choice :)
Sounds good to me. Let me know what sub will go in there so I can design one ahead of time and you'll see how a real sub box is built. I'll need 3/4" MDF, carpeting of your choice, 3M spray adhesive, and a terminal cup. I can probably find a terminal cup somewhere in my boxes of home theater speaker parts; they're $5.50 each (for the good ones at least). I usually buy the wood glue by the gallon because I go through it so fast. Any Saturday should work for me, but let me know ahead of time when you want to swing by. It should take about 3 hours to build one.
 

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Discussion Starter · #10 ·
Alright cool. I'll let you know here soon (a week or two) what I'm thinking of getting as far as stereo stuff goes.

If I don't hear back from Insane Speed Motorsports, I'll dump the money I budgeted for those upgrades into my Electronics budget (Retro Fit / Stereo System) and I'll have more money to play around with.

Saturdays work best for me as well, and 3 hours isn't bad at all. I assumed it'd be most of the day.

I'll pm you when I get more figured out.
Well, there will probably need to be a few breaks in between to let some of the glue dry before we continue onto the next part, but I don't see it taking more than 5 hours. I'll keep an eye out for your PM.
 

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Discussion Starter · #12 · (Edited)
I know I asked you about a box for a JL sub but I forgot I had 2 MB Quartz rwe-204
Qes-.631, Qms-6.5, Fs-37, Vas-30.9, Sd, Xmax, and RMS Power handling-150w. I have a A/D/S P240 and P440 not sure which to use but one will power the door speakers. I was going to try and put them in the left and rt corners of the car and going for sq. I can cut the wood and put together but I am terrible at design lol. I could not find the Sd or Xmax on the subs.
What size sub are they technically? I'm seeing 8", can you confirm?

I can't find any information regarding those amps. What are the power ratings and at what impedance? Do you have the data sheet for them?
 

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Discussion Starter · #15 · (Edited)
I looked them up and confirmed they're 8" subs.

Qts is too high to be used in a sealed box. Realistically, these are designed for ported boxes or free air use in rear decks, although they'll bottom out with anything over 50W in free air.

If you want to use them though, you'll be pleasantly surprised at what they can do in a ported box, if you give them the space...

Put them in a ported box, ~1.15 cubic feet (gross) per sub and two 2" round ports at 12.5" in length for a tuning of around 33hz. You could lengthen the ports a bit, but I very highly recommend you use double flared round ports. These in particular, and you'd need 4 of them if you're building two boxes.

Precision Port 2" Flared Port Tube Kit 268-348

If you're only building one box for both, build it to 2.3 cubic feet and use two 3" ports at 13.45" in length each, or one 4" port at 11" in length.

Precision Port 3" Flared Port Tube Kit 268-350
Precision Port 4" Flared Port Tube Kit 268-352

Line all of the box walls except for the baffle with 2.5-3" of acoustic foam, mineral wool, or fiberglass insulation pad (the fluffy stuff unless you can get Owens-Corning 703 rigid fiberglass board).

Frequency response looks great. Very good extension for an 8" sub.


Excursion control at 75W is good. I think you could safely give them 100-150W each.


Vent velocity is good and low, which is where it should be if you want to prevent port noise, chuffing, or de-tuning.


Personally, I'd build these subs if I were you. They're low powered enough to where you can use 1/2" MDF with some bracing inside and a 3/4" MDF baffle instead of 3/4" MDF all around. It will save you a bit of space and you don't really need 3/4" MDF all around with low powered 8" subs if you're tight on space. The box requirement is a bit big, but they'll put a big smile on your face if you build them, I guarantee it.
 

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Discussion Starter · #16 ·

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Discussion Starter · #20 ·
I also have a infinity 475a amp and a arc audio fd1200.1 amp should I use one of those instead of ads
I would go with the Infinity. You'll have a bit more power out of that and you have some more power to be gained.

Would you suggest building separate boxes or build one box
It all depends on where you want the subs. It would be easier and cheaper to build just one box.
 

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Discussion Starter · #23 ·
ok the infinity is a 4 channel amp for the fronts and rears 75 watts RMS x 4 channel at 4 ohms and ≤ 1% THD + N 180 watts RMS x 2 channel at 4 ohms, 14.4V supply and ≤ 1% THD + N
Yep, that would work very well. It's generally a good idea to overpower the subs to prevent from clipping the amp.

I should be starting to get things ready by the end of the month. Out of the 2 subs you suggested, Aura and Morel, the Morel isnt the SC correct? And which one of these are closer to being discontinued? Id like to get something that will be on the market for a few years and still offers some type of support in case I pop it.
Correct, I referred to the Morel Ultimo, not the Ultimo SC. I think both the Aura and the Morel subs would work excellently, and both companies have a very good reputation. As for popping it, that would be unlikely.

When referring to high quality subs, the only way to destroy a sub is to drive it beyond its mechanical excursion capability and cause it to bottom out (you'd have to be abusing it pretty badly to do that), or to send a clipped signal from the amplifier. Sending a clipped signal only really happens when you underpower a sub. Any high quality amplifier that provides a bit more power than the sub is rated for will be able to provide clean power. Both of these subs are SQ subs and should be treated as such. They're not SPL subs designed for massive amounts of synthetic bass, and they should be respected as musical instruments.

If you were very concerned about blowing one of the subs, I'd direct you to the Image Dynamics subs. The IDQ and IDMax both have removable cones, which you can replace in 15 minutes. The cone assembly includes the rubber surround, the suspension/spider, and basically every moving part. The only thing remaining once you remove the cone is the magnet and the frame. Re-cone kits can be purchased directly from Image Dynamics. These are some of the only subs I know of that can do this.

That said, if you treat a sub well and give it clean power, I don't see this being an issue. I have 4 IDQ V2 subs that were made about 10 years ago that work perfectly. Last year, I sold a Focal free-air 11" sub that was made in 1997 that also worked perfectly. So long as you treat it well, don't abuse it, and give it clean power, it will probably out-last your car.
 

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Discussion Starter · #25 ·
Listen to this man! He knows his stuff.

Take his criticisms as positive ways of saving you time and money down the road :)
:sigh:

Thanks man. I'm not doing this for personal gain. If I tell anyone something they might not want to hear, I'm doing it for your own good, so you get the most out of your budget and efforts and don't make the same mistakes I did when I was starting out.
 

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Discussion Starter · #28 ·
Do you have any pics of custom enclosures you've built? I remembered you mentioning in a different thread before about building custom enclosures that fit into the Eco trunk floor and thought it was a cool idea.

Good luck with your business, I'm sure I'll be hitting you up next time I have audio questions.
I don't have any pics right now aside from a few completed boxes. I'll start building a box today to give people an idea of what these look like and will take pictures along the way. Most of the custom part of this is being able to tailor the box to someone's specific subs and specific car's cabin transfer function, something to this date I haven't seen anyone be able to do. Most people will just equalize the **** out of it. I prefer to do it with the box so you don't need a parametric equalizer.

I'll try to find time to work on an enclosure that fits into the eco trunk floor. That's going to be a bit more of a challenge as there are a few angles to worry about and several cuts to be made.
 

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Discussion Starter · #30 ·
Hey Xtremerevolution, I may be in the market for a box. Here is some of the info you said you'd need.

Alpine SWR-843D (SWR843D) 8" Dual 4 ohm Type-R Car Subwoofer/Sub
Boston Acoustics GT-2125 (gt2125) GT Reference 2-Channel Amplifier

I'm looking to maximize trunk space, while making sure I have some SQ. I think that sums it up.
Didn't I just recommend you those? lol!

As I mentioned, I can build a box like that for about $125 plus shipping.

I can have it done and shipped out within a week.
 

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Discussion Starter · #32 ·
do you know how much shipping should be? Chicago to LA my zip is 90803. Also, could you send me the design you were thinking so i can have a chance to get my head wrapped around what it would be like.
There's not much to the design. I would probably decide on somewhere between .4 and .6 cubic feet. The baffle would be two sheets of MDF; one 3/4" sheet that the sub mounts to, and either a 1/2" sheet or a 3/4" sheet on top of that to allow the sub to be recessed. I will add some bracing to ensure that the walls don't flex, although an 8" sub really won't have any problems. I also line the back wall with mineral wool which I get from ATS Acoustics to absorb any higher frequencies from harmonics. I'll install a quality terminal cup, use 12 gauge wiring inside, and carpet it with whichever color you want. The side panels will be recessed in 3/4" so that you can have edges to grip onto in order to lift the box or move it around easily.

I hope this answers your questions. If you're looking for specific dimensions, that's something we can figure out as dimensions are never set in stone, but the box has to be tall and wide enough to mount the sub without drilling holes into the top and side panel, and deep enough to fit the sub itself with at least 3/4" of space behind the sub itself to allow the pole piece vent to breathe.

Shipping to LA would probably be around $25-$40.
 

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Discussion Starter · #33 ·
After trying to figure out where I'd put these pictures, I decided that this thread would be the right place for it. Since not everyone has a good understanding of what goes into building a custom sub box, I've been taking step by step pictures of my progress making mine, which is how I build all of my sub boxes. If you have a slow internet connection, I'm sorry. These are high res photos. Click to enlarge.

First, I start with bare sheets of MDF. I use MDF because it's a dead material (doesn't resonate easily or let sound pass through it), and it's cheap. Last time I bought it, it was $32 for an 8ft x 4ft sheet. The downsides are that it's heavy, the dust created is very fine and isn't particularly good to breathe on a daily basis, and it wears out saw blades and router bits more quickly than real wood.


The sub I'll be installing is an Image Dynamics IDQ15 V2 D2.


I flush mount all of my sub boxes because they look great and it better protects the sub from foreign objects in my trunk. The flush mount panel also adds rigidity to the baffle, which is important. To decide if I want 1/2" or 3/4" MDF for the flush mount, I measure the sub itself to determine thickness. Here we have just under half an inch.


"1/2" MDF" is just a bit thicker than 1/2"


"3/4" MDF" is just a bit thicker than 3/4"


Got the measurements and the MDF on the table saw. Carbide, fine-toothed blades aren't necessary for MDF, but I was too lazy to change it out for my standard 12" blade this time for just one box. As always, measure 3 times, cut once. While MDF is cheap, time isn't always.


All panels are cut. From left to right, you have the back, front, and flush mount sheets, then the top, bottom, left, and right sheets, and then you have two more from which I'll cut out the bracing.


Got clamps? Sadly, I actually need about 2x this many if I want to build two boxes at a time. You could do it with less, but it would take longer. You'd need at least 8 clamps to build a good sub box.


Lining up the sheets to make sure they fit well. Once you've measured 3 times and cut once, you mock fit everything to make sure you don't glue up something that won't work, just in case you screwed up somewhere. I'm leaving a 3/4" gap on the edge there so I have something to grab when you try to lift the box out of the trunk or move it around.


Glue, and a good amount of it. That's all you need to attach these panels. No screws, no nails, as those are 100% unnecessary. If you've ever welded before, you'll know that the weld is often stronger than the steel. This applies in this case. Once the glue dries, the joint is stronger than the MDF itself. There is zero need to use anything else. I use and highly recommend Titebond II.


Clamp down the first panel. Have a roll of paper towels ready to wipe off the excess that gets squeezed out.


Two panels are now clamped together tightly.


...three panels. Are you seeing why you need so many clamps? I like to clamp every 6 inches for an even and uniform clamping pressure. You don't want to over-clamp one specific spot as you can create an indentation in the MDF on the edges and cause it to split.
 

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Discussion Starter · #34 · (Edited)
Wipe off the glue on the edges before it drips all over the floor. Not recommended for doing on a carpet, lol.


Now it's time to let it dry for 20-30 minutes


In the meantime, I started on the bracing. I cut these sheets a little bit higher than needed so I have somewhere to drill the pivot hole for the circle jig. I then draw a line across where it will be cut.


Set up the jasper circle jig on the router. I can cut circles up to 18" in diameter in increments of 1/16"


Nail down the boards to be cut so they don't move. 2.25hp router in your hands has a lot of potential. I usually nail this down to a scrap piece of MDF, using a pin nailer. 22 gauge, 1" long pins are long enough to hold it down securely, but allow me to pop the panel out with a few whacks from a mallet.


Precision routing. To preserve the bit and keep it from overheating in MDF, you have to cut 1/4" or less of material at a time. Usually takes a few sweeps, but it's better than burning the bit and having to spend $30 on another one.


Trimming the edges with my 8" compound sliding miter saw. I have this hooked up to a shop vac to keep dust under control.


Got the second brace cut out...


Cutting out the outer baffle...


Test fitting the sub in the flush mount cutout. Perfect. I left 1/16" of gap to fit the carpeting.


Forgot to take a picture of the main baffle cutout, but here's the test fit for that. Also perfect.


Bracing is all trimmed up. Gluing it in place...


Gluing on the last side panel. Don't forget to wipe the edges!



It's coming along!


All dried up!


Gluing the main baffle and flush mount panel together.


Test fitting the sub. Perfect fit! It's almost a bit too tight as I still need to put carpeting over those edges. I'll probably have to persuade the sub to fit in there.


Time to glue some mineral wool. I get scrap mineral wool from ATS Acoustics for fairly cheap in a large box. The idea is to absorb the higher frequency backwaves from harmonics and not have them bounce around in the box and hit the cone again. The fill also helps make the box "sound" like it's bigger than it really is, which is always good when you're low on space. It helps smooth the frequency response. This all gets glued down with 3M adhesive spray. I've tried other adhesive sprays and nothing compares. I use mineral wool because it's a superior material. ****, they make wall acoustic panels out of it. Much better than polyfill, and much cheaper (and better performing) than acoustic foam. Doesn't have to be pretty here, just functional.



I'm filling everywhere but the center. You'll also noticed I trimmed out the center of the braces. This is because once I mounted the sub, I discovered that the mounting depth wasn't correct on the manual from ID (or I read it wrong), and the rear pole piece vent was a bit too close to the bracing for comfort. I trimmed them out in no time. I'm keeping the mineral wool away from there so the pole piece vent can breathe easily.


Mineral wool is all glued up and done. This is where I stopped last night. More pictures to come when I make some more progress later this week.
 

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Discussion Starter · #36 · (Edited)
Got a bit more done today. I attached the baffle to the rest of the box. The braces lined up just like I wanted them to according to the cutout of the sub.





I'll run down to the fabric store tomorrow to find something fun to cover it with. Most people prefer just a plain black carpet, but I like to mix it up a bit. Last sub box I made for myself for my IDMax10 used faux tiger fur. Nothing like a sub box that you want to snuggle with by the fireplace.

:blink:



I also made one with black shag once upon a time...
 

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Discussion Starter · #38 ·
Wow, awesome pics, and how to. I was under the impression that the panels were assembled with screws. good to know.
Yeah, screws are the worst way to build a sub box. It's extremely easy to split the MDF when using screws, and there's no point to it when the wood glue joint is stronger than the MDF. One advantage to MDF is that it absorbs water very quickly, so when you clamp it together with wood in between two edges, the wood glue absorbs as it dries and hardens structurally to the MDF.
 

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Discussion Starter · #39 ·
Got the clamps off the box.



Test fitting in the trunk. This is exactly what I wanted it to look like. I wanted it to just barely fit under the rear deck beam, and be just deep enough to not go over the ridge on the carpeting floor. Can't wait to hear this thing play.




Got the smaller jasper jig on there to make the cutout for the terminal cup



A perfect fit again. I love circle jigs!


Solid screw-type posts on this terminal cup. No spring loaded terminals for me.


Gave the box a good sanding with my RAS (random orbital sander) and put the sub in for a test fit.

 

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Discussion Starter · #41 ·
Hey XtremeRevolution,

That box looks way awesome, I really want to see if can do this on my own, that would be a mighty task in itself. I was wondering, does the box shape itself effect sound quality? Such as cube shaped as opposed to wedge shaped. You said you design the boxes for free, right? I'd like to have a go a building my sub box, so if you could work up the designs for me that would be great. Also, I was looking at the sub you recommended for me, Alpine SWR-843D (SWR843D) 8" Dual 4 ohm Type-R Car Subwoofer/Sub, and from the web photos, since i have not bought it yet, looks like you screw it to the box from the inside? is this right? or is there a small rim that just covers the screws after you screw it in from outside the box? This sounds like a ridiculous question, but from what i'm seeing I can't help but ask.
Having owned a few Type-R subs in the past, I can say that they do indeed have a trim ring that get placed over the edge to cover up the screws.

I can design you a box. Are you limited on space? This sub does very well in both ported and sealed boxes. It really comes to life in a ported box, but if you're low on space, sealed works very well too.
 

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Discussion Starter · #44 ·
I was hoping to conserve as much space as possible. Is there any difference between rectangular and wedge like boxes?
Sealed will be the way to go. Doesn't matter if you go rectangular or wedge as long as you clear the sub when you mount it. The wavelengths of the frequencies this sub will play are much, much too long to be affected by the shape of the box in this size.

Go for .7 cubic feet sealed gross volume. Mounting depth is 4.525". If you want to try to make a wedge, you can use this site to help you crunch the numbers.

Speaker Enclosure Volume Calculator

If you make a double thick baffle, don't include the outer flush mount panel in those dimensions. I personally wouldn't try to make a wedge and just make a rectangular box. Due to the ridge you have right before the seats in the trunk, you won't benefit much if at all from something like that.

After seeing these pictures I want you to build my casket albeit I'm only 22. Just make sure my 4 12's have their place haha
Speaking of those 4 12s, my IDQ15 build is now going to be second priority to a new build (yours), and this one's going to be big. I brought home two 4x8 foot sheets of 3/4" MDF today. Pictures will be posted of my progress. My deadline is to drop this off at FedEx on Sunday.

 
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