Car Audio - Custom Door Panels

It is fairly simple to build custom panels to cover up amplifiers, processors, and other components like the pros do. All you need is to follow the step by step methods presented here, some woodworking skills, and some basic tools such as a circular saw, jigsaw, router, sander, drill, hot melt gun, a very sharp knife (carpet knives work great), stapler, etc.

Most panels follow the same construction process, no matter what materials you use: Making a template, building the frame (base), raising (if necessary), filling, smoothing and covering the panel.  For example if you are making a door panel, you would first make a frame out of wood, then round off the edges by filling them with Bondo and covering up the whole thing with vinyl.
  

Step 1: Making a template

One of the easiest (and cheapest) methods is to use cardboard for the template. For example, you are making a one-piece panel for the trunk, that will go around a subwoofer and a couple of amps. Cut a (straight) end of the cardboard box and place it next to an amp. Keep cutting pieces of cardboard and gluing them with hot melt over each other to make a big template consisting of glued pieces of cardboard. This way, instead of figuring out the shape of one big piece, you will have to figure out the contour of a small part of the whole panel at a time.

Once you come up with a template, make sure you have no gaps. If you have to bend the template to get it in and out, you will have trouble with the final panel, since the panel will most likely not bend. You might want to split the design in two or more panels. Plan ahead of time what material you are going to use to cover up the panel, and subtract the thickness of the material from the panel. For example, if you are using vinyl, you might want to reduce the outline of the panel by 1/8", but if you use carpet, maybe 3/8" will work better.

Place the template over the material you are cutting. Trace the outline with a pencil.  Cut using a circular saw on the flat parts, and a jigsaw on the curved parts. Use good saw blades to get smooth cuts (this will save you some work later).

After the panel is cut, take it back to the car and make sure that it fits, check that whatever material you are using to cover it up fits in between the gaps. If you took the time making a good template, then the panel should be a pretty good fit.

Step 2: Raising the panel

If you are making a flat panel, then go to step three, if not, keep reading. On this panel we are making as an example, we are planning to raise edges around the panel to outline the amps. Make a square "ring" around a hole and screw it to the main panel. Then, make another ring (this one smaller outside), and screw it on top of the first ring. Keep going until you get to the desired height and shape. (It is a lot easier to do various 1/4" levels, rather than trying to shape one thick piece of wood. You only have to get an approximate shape. The gaps will be filled on the next step.   Fiberglass can also be used here.

Step 3: Filling and smoothing out edges

On the previous panel, there are gaps in edges of the layers of rings. Fill the gaps using a material such as Bondo. Try to get a shape as close as possible to what you want. Once the filling material is dry, sand the panel down.   Additional layers might need to be applied for a good finish.

If you are using a thin material to cover up the panel, such as vinyl or grille cloth, then you need a very smooth surface. On the other hand, if you are using carpet, or padded vinyl, then you don't have to worry about sanding the panel down too much.

Step 4: Covering the panel

Most of the time, spray glue is the adhesive of choice. You can get a can of 3M (or similar) spray adhesive at any hardware store for about $10. Cut the covering material (i.e. vinyl) around the shape of the panel, leaving at least a two-inch overlap. Place the covering material upside down and spray the glue over it. Also spray the panel. Let sit for about a minute, and place the panel on the covering material, stretching the fabric over the panel. Use a clean rag on the surface to make sure the whole top of the panel is in contact with the fabric. Flip the panel over and spray glue on the overlap, and edges of the panel. Cut the overlap as you go to fit edges and corners. It is good practice to staple the fabric on the underside, since glue will sometimes not hold very good when the car gets hot.

Figure on your initial design how you are going to hold the panel. You do not want to have screws messing up your panel's finish.  Pressure fitting requires a bit of skill, but is the cleanest way to go.
  

Materials

If you are using the panel just to cover up an install, the you don't need a 3/4" particleboard panel, adding more weight to your car. Plywood will do just fine. On the other hand, if you are building a sub box, you don't want to use anything that will bend. Common panel materials are particleboard, MDF, plywood, various metals, Plexiglas and other plastics, even fiberglass.

To fill gaps and smooth out surfaces, you usually want a material that will adhere to the panel extremely well, and will be hard. Most installers use Bondo (car body filler), epoxy (for small fixes), and fiberglass.

There are many materials used to cover up panels. The most popular are carpet, vinyl, leather and various types of fabrics ranging from speaker cloth to velour. You can also add padding under the cover material.

There are many materials and finishes available. It just takes practice to see what material is best for each application. Even though there is no single way to build a panel, following the above guidelines will give you an idea of the basic process. The rest you will just have to figure out by trial and error. Even though whole panels can be build using simple tools such as handsaws and sandpaper, power tools will greatly reduce fabrication time, especially when sanding.