Jump to content


Fiberglass Amp Rack 101: Build a Custom Fiberglass Mold for Amplifiers, Every Step

Recommended Posts



What’s up ladies and gentlemen of the car audio world? Today I bring to you the all inclusive Fiberglass Amp Rack 101 Lesson! Allow me to insert my shameless plug and say that if you enjoy any part of this tutorial, or learned something new, please post a comment, rank this thread, and share with your friends! Also I love when I get new subscribers on my YouTube channel! (The SECRETS of Car Audio Fabrication! - YouTube ) Other than that let’s review what you will learn shall we?




First off I know I know, this looks like a ton of reading, and a ton of work, but it really is not, it just seems that way because I am outlining every thing I have learned over the years of many car audio installations. When I started learning this I would have done ANYTHING for a write up with the tricks and techniques I am going to show you, but it didn’t exist, so again while it might seem like a lot to read it WILL be WELL worth your time to read through this and watch the videos. Note that some of the videos or somewhat of an “update” to my progress within the step, where as others are much more of an actual step by step instruction. The videos have a run time of a little over an hour, so grab a frosty beverage and some food and sit back! That being said there are a million different ways you could construct an amp rack, this tutorial will cover what I have learned and found to be very effective means of building a professional quality amp rack. Note that for the sake of length some sections of this lesson may refer to previous lesson posts I have made, in these cases I will provide a link for you to visit so that you may learn that technique as well! Also note that the quality of my videos improves throughout the series. Please watch all the videos to gain the full experience! In order to watch all of the YouTube videos is one go, please view the YouTube playlist here:



Note that each step within this write up also has the video thumbnail, with a link to the video below it.


The Process:

Before we begin allow me to briefly outline the process that will be covered. By understanding each step involved you are well on your way to an amazing fiberglass amp rack!


1. Designing the Layout

2. Skeleton – The Foundation of your shape and Making Templates

3. Prepping Templates and Skeleton for Molding

4. Applying Fabric – The Skin of your shape

5. Glassing and Strength

6. Smoothing and Prep for Finish

7. Adding Plexi and Inserts

8. Wrapping the Amp Rack – Vinyl, Suede, and Carpet

9. Final Thoughts


Let’s begin!


---------- Post added at 02:14 PM ---------- Previous post was at 02:13 PM ----------


1) Designing the Layout:


Before you even cut your first piece of wood you are going to want to carefully consider your layout. First off most all amplifier racks should be designed with two pieces in mind. They are 1) The Mounting Structure and 2) the Beauty Panel. The mounting structure is what your amps and equipment will mount too and the beauty panel is the structure that will hide all the wiring and effectively show off your amps. Note that your amp rack could be designed that both these functions are in one piece, but in my case they are separate.


Next you need to layout the equipment. To effectively do this take a picture of the bare trunk and sketch where each piece of equipment will be, and then what you want the finished product to look like. Luckily I have access to modeling software so I perform this step on a computer. The video shows my first step of the design. This is also a great phase to consider the materials you will use to finish the amp rack and their seamless integration into the vehicle. I strongly advise you to consider the “less is more” philosophy in this phase. Often times the best installs are those that are the most simple.



How to Design an Amp Rack Layout - Car Audio Custom Fiberglass - YouTube



Fiberglass Amp Rack Update! Explanation of How to coming soon! Templates ready to go! - YouTube


Before continuing to your skeleton here is an excellent list of questions to ask yourself about your design to minimize issues throughout the build.

• Have I accounted for enough room for all amplifiers, distribution blocks, equalizers/crossovers, and wiring?

• How will the wiring reach my equipment?

• Is there enough airspace around my equipment for proper cooling per the manufacturer recommendations?

• Will my equipment be secure in the way I plan to mount it?

• Can I easily access all fuses, and adjustments on the equipment?

• Are all functions of the vehicle still possible? (Moving Seats, Trunk Closing, etc)

If the answers to the above questions are yes, lets continue onto making your wooden skeleton.


2) Skeleton – The foundation of your shape:




So its time to get to work building your skeleton which will be the foundation for your amp rack. I recommend building your Mounting Structure for your equipment first. This will require basic building techniques so I did not outline much of it within the videos. Some tips are to utilize good mounting techniques for securing the base of the mounting structure. Some of these techniques are to use nutserts (threaded rivets) for mounting to the sheet metal of the vehicle and t nuts for mounting equipment to wood. They are outlined in the following two videos:



Thread Setter! Tool of the Week! Use to mount car audio items to sheet metal! Threaded Rivets! - YouTube



How to Use a T Nut ! How the Car Audio Fabricator Installs them - Used in my Fiberglass Amp Rack! - YouTube


Once your mounting structure is complete you will want to start determining what shapes you would like to use for templates that will cover the amplifiers or be around them. I cover how templates are made in a totally separate how to series, as they are pretty involved steps, but once you learn them you are on your way to taking your install to the next level. Check out that how to series here:



When it comes to making the Beauty Panel skeleton you are going to want to utilize techniques like router tricks to make pieces that fit within one another perfectly. You will also want to use techniques that allow you to mesh similar pieces of wood into one another to create separate pieces of the amp rack so that the amp rack is an assembly, rather than one permanently conjoined part. Having an amp rack that is multiple pieces that are joined together by bolts and screws is much more effective than an amp rack that is glued or otherwise permanently joined. You want to have access to the equipment.


The methods and steps to effectively doing this are outlined in the following video:



How to build a wooden skeleton foundation - Amp Rack 101 - Car Audio Fiberglass How To - YouTube


Once you have all your skeleton pieces built for both supporting the equipment and hiding the equipment you are going to want to prepare the skeleton for fiberglass, the professional way.

Share this post

Link to post
Share on other sites

3) Prepping Skeleton and Templates for Molding


Here is where the rabbeting bit and the router come into play. If there was ever one ‘most important step” within the process I would say this is it. This step is often skipped and leads to tons of more effort in the fiberglass stage. Pay close attention to the steps performed here, and follow them!




How to rabbet a groove for fiberglass treatment - Amp Rack 101 - Car Audio Fiberglass How To - YouTube


Following the steps in the video will allow you to cut a perfect step in your skeleton pieces. This step will lead to a flush fiberglass surface that is easier to sand and fill with body filler.



4) Applying Fabric – The Skin of Your Shape




Here is where your design will really start to become a reality. In this step you are going to stretch material and adhere it to the bounding surfaces of your amp rack. This is where properly preparing your amp rack skeleton will really pay off.


Within the video you will see how I stretch the material properly in a manner that avoids sags and wrinkles, and also how to easily adhere the fabric and trim it perfectly.



How to stretch fabric fleece - Amp Rack 101 - Car Audio Fiberglass How To - YouTube


Upon completing the stretching of your fabric you are ready to move onto adding some fiberglass strength!


5) Glassing and Strength:

Now that you have a super clean and functional fabric surface prepared it’s time to add some strength! After all we want our fiberglass amp rack to last for years in the harsh automotive environment, so let’s get to work making it ready for the abuse!


In this step you are going to learn to apply fiberglass resin to the fiberglass, you are also going to learn how to apply fiberglass chop mat. Though there are different techniques that can be used in this stage, this is the method I use and have never had any issues. Note that if you do in fact have access to the “rear” of the panel it is advantageous to apply the fiberglass mat to the rear. This allows for a smoother surface to sand later on, but in my case I did not have this option.


People who are new to fiberglass are often surprised how simple this step actually is! Watch and enjoy!



How to add fiberglass resin and strength - Amp Rack 101 - Car Audio Fiberglass How To - YouTube


---------- Post added at 02:16 PM ---------- Previous post was at 02:15 PM ----------



6) Smoothing and Prep for Finish:


So your fabric surface is now nice and strong! So that means it is now time to smooth things out and prepare for the finish that you plan to apply to the fiberglass amp rack. This steps video will teach you how to properly smooth the surface using a high quality body filler. It will also show you techniques that can be used to help decrease the sanding time, a HUGE time saver! Two key points here:


Milkshake: If you have a relatively horizontal surface you can use what is called a “milk shake” to get things nice and smooth. This is accomplished by mixing body filler and resin with a 3:1 ratio. 3 Parts body filler to 1 part resin. You then add the proper amount of hardener and MEKP that corresponds to the amount of body filler and resin used. Upon mixing you will note that the body filler will lay down extremely well, and be very level, the downside is that you cannot really do this on vertical surfaces, and the body filler also becomes a little more difficult to sand.


Green Stage Sanding: When sanding body filler you want to be sure you are sanding in the “green stage”. What this means is you want to pay close attention to body filler as it is drying. Every 5-10 minutes take a piece of sand paper and try sanding the body filler. If the body filler still seems like “liquid” then it is NOT ready to be sanded. But if the body filler sands with a “foam-like” consistency, almost as if you are grating cheese, then it is ready to be sanded. You can really sand very effectively in this phase. This is also the key reason to purchase high quality body filler. With Rage Gold you will find the Green stage lasts for 20 mins or more. With Bondo brand… well there doesn’t seem to be a green stage.



How to - Body Filler and Smooth Surfaces - Amp Rack 101 - Car Audio Fiberglass How To - YouTube


Note that in the video I am prepping for a vinyl surface, not paint, so I only sand up to 150 grit. If you were doing paint you would want to sand smoother for the primer application… but that is a different How To.


7) Adding Plexi and Inserts:




Now that you have smoothed out your main surface it is time for a step that can really make your install look amazing, and help tie everything together. In my design you can see the shape that I utilized over the amplifiers. It is a rounded rectangle of sorts. In order to make the entire amp rack look appealing I want to carry that design to each piece. In order to carry it to my amp rack “trim ring” I want to incorporate the rounded rectangle shape. I do this in the form of an “insert”, and what better to accent the insert than a piece of plexi glass that can be back lit, or have a logo applied.


In this step I show you how through using router skills you can make an exact plexi glass shape and integrate it behind an insert. I also show you how you can use foam tape and body filler to make a perfect gap for the materials you will ultimately finish the amp rack trim piece and insert with. Big tips here are to use a high quality body filler (as you will likely be doing small detail sanding) and to make sure you use foam tape with enough thickness for the materials you use to finish the pieces.



How to make Fiberglass Insert Templates - Amp Rack 101 - Car Audio Fiberglass How To - YouTube


8) Wrapping the Amp Rack: Vinyl, Suede, and Carpet:


So it’s finally coming all together! You’re ready to finish the amp rack off! In the first video you will learn how I wrap “basic” panels, which basically does not require the use of a heat gun, but requires you to rabbet the edges of the panel for a clean finish on the rear side. In the second video I will show you how to wrap more complex panels, which requires a more aggressive adhesive as well as the use of a heat gun when using vinyl to properly form the piece and avoid wrinkles.


It is very important that you take your time in this step, do not attempt to secure materials before your adhesive is tacky. If you try adhering the materials to early will pay for it later when the material pulls away from the panel. It is also important when wrapping a complex panel to utilize high quality glue, as I will recommend within the video.



How to Apply Vinyl or Suede - Car Audio - Amp Rack 101 - YouTube



How to wrap an Advanced Panel with Vinyl - Amp Rack 101 - Car Audio Fiberglass How To - YouTube

Share this post

Link to post
Share on other sites

9) Final Thoughts:


Once all your panels are wrapped you’re obviously ready to piece things back together. It is important to verify things are perfectly secure. The vehicle can be a very dangerous place in the event of an accident, so insure everything is held firmly in place.


If you enjoyed this tutorial please comment below, if you utilize any of the methods in this tutorial please feel free to share pictures within this thread of what you made! I love seeing what my lessons have helped people create! If you have any questions please feel free to post below!


Good luck!



Share this post

Link to post
Share on other sites

Definitely was a fan of the tut, man. Makes me feel more comfortable about tackling this further down the road in a Tahoe build if I can't fit my amps under the seats. Not to mention, the sh*t you don't hear in CA vid was epic (at least for me).


Keep 'em coming, man.

Share this post

Link to post
Share on other sites

Nice write-up and videos. I'll probably be using this during my next build.

Share this post

Link to post
Share on other sites
Nice write-up and videos. I'll probably be using this during my next build.


Awesome man, share pics with me when you do.

Share this post

Link to post
Share on other sites
That took some serious time and dedication writing that up. I vote for sticky.:thumbupw:



Thanks man, appreciate it, it was a ton of work

Share this post

Link to post
Share on other sites

Looks good man, lots of great tips. Its helpful for me as I plan on building a amp rack soon. Though it wont be as complicated as some of the work you do, you have given me lots of good ideas.

Share this post

Link to post
Share on other sites


Praise be to you!


Looks good man, lots of great tips. Its helpful for me as I plan on building a amp rack soon. Though it wont be as complicated as some of the work you do, you have given me lots of good ideas.


Integrating some of the ideas I show you can be very easy, but at the same time really step up the quality of an install, I challenge you to try them out, it will pay off for you.

Share this post

Link to post
Share on other sites

Man I seriously cannot wait for it to warm up here so I can get back in the garage, an update for those of you who enjoy my youtube videos, in the downtime I have been learning some of the Adobe Product suite, I have also invested in green screen equipment, and new microphones, the next videos are going to have a big step up in quality!

Share this post

Link to post
Share on other sites

I think a lot of people could benefit from the videos in here, just don't want it to go un-noticed.

Share this post

Link to post
Share on other sites

I would like to request this be moved to the reference database, spent a lot of time on the write up, and dont want this thread to die off.

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

  • Similar Content

    • By chetomatic
      Does anyone know the best way to put two 12" JL subs under a seat? I have an '00 Jeep Grand Cherokee and I have a feeling I'm going to have to make two custom fiberglass boxes...I've searched for custom boxes but they don't seem to exist. Also, if anyone else has any other ideas on how to accommodate two subs somewhere else than my trunk (I have 3 JLs back there) or under the back seat, it would be greatly appreciated. Thanks.
      EDIT: I can also reverse it (put the three 8" subs under the seat and the 12s in the trunk) if that makes the process easier...
    • By muddin wolvy
      Hello all,
      I'm just now getting back into car audio and need some assistance in finding my ideal sub...
      1- 15" sub (1 only)
      2- respectable SPL from sealed fiberglass box.
      3- performs well with minimal airspace. (maybe 3ft^3?)
      4- handle anything below 2500 watt RMS. (closer to 2500 the better)
      I know I need more space and I know ported = godlike qualities, but I'm experimenting with fiberglass and the location I've chosen is relatively small.
      The amp I have is an Alphasonic PMA1200DA. Just bought it today (used) for $150. It works and I believe is the Craigslist deal of the year haha!
      Anyway, thanks in advance
      And try not to flame me too much...
    • By gnesterenko
      Ahoy all.
      So I've looked at many-a-build log and have decided to go with the hang the amp-rack from underneath the rear deck design. [The sides of the trunk aren't really an option. The floor of the trunk is to be kept clean and open (for ski/snowboard season). Not enough room under the seats in the cab. And I didn't like the idea of mounting amps to the back of the rear fold-down seats. Which left the rear deck. Upside down I'm far to weary of to attempt.]
      So! Below is the rough design drawing of what I'm looking to do. While I'm relatively happy with the design as it is (though feedback is appreciated), one particular sticking point for me is the rack slide hardware. I can easily find plenty of cabinet slider racks to accomodate the weight & size of the equipment. This is an acceptable solution, however I can see the point of difficulty being making any adjustments, and even connections on the backs of the amplifiers.
      What I would really like to have are, sort of 2 stage slides. Stage one being that it simply slides out. Once the maximum is reached, the slide becomes a hindge, allowing the entire amplifier rack to fold downward, leaving the control bits of the amplifier facing upward, allowing for easy adjustment, maintenance, plugging/unplugging wires, etc... Once we're done, filp the rack back in line with the slide, push it back in, and lock it. I know I've used cabinets or whatnot that have used this type of slide rack hardware, but for the life of me, I have no idea what something like that would be called or where to look for one. If anyone knows what I'm talking about, please, let me know.
      Design Drawnings:
      Amp rack in its 'locked' state. Though not illustrated, locking mechanism would be either
      A) two simple security bolts on either side locking into the two frame MDF pieces (actually these may be 2x4's instead of MDF). or
      B) The bottom support frame MDF piece (the piece connecting the left and right side of the rack frame, underneath the actual movable portion) would be cut back slightly at the front, with a hindged flap piece at the very front that would fold up to 'lock' the rack in place... this would allow for a carpeted 'cover' door for the rack, improving looks, that also serves as the locking mechanism ensuring everything stays in place while the vehichle is in motion.

      Amp rack in its 'extended' state. Or per above, the end of the first stage of the slide.

      Though not drawn, the 2nd stage of the ideal rack would be after this point, where the entire front of the rack folds down while the rear is hindged, by this magical slide, at the frame.
      Anyway, that's my spiel. Any feedback is appreciated and again, if anyone knows where I can find my magical 2-stage slide hardware, I would praise and sing your glory for days to come.
      Posting from work, so need this disclaimer:
      "The views expressed here are mine and do not reflect the official opinion of my employer or the organization through which the Internet was accessed."
    • By pilotdog68
      I am somewhat lazy and dont have access to many tools, so I went out and bought a cheap box made out of ~5/8 mdf. I didnt realize how important box strength is. Some people say you can strengthen the box by adding dowels, or by coating the inside with polyester resin. one guy said he painted the inside with wood glue. do any of these work or are they all bull? if they do work, do they do enough to be worth the cost/hassle? are there any other suggestions for a quick fix? its a 10" sealed .70cf box, will run a 300wrms sub.
      thanks for helping the newb here
    • By bcirilla
      I'm looking to have some custom work done to my truck. I want my dash piece to be reworked with fiberglass to house an ipad. Any reccomendations on where to do business would be greatly appreciated.