Attach the two filler pieces to the underside of the rear deck with angle brackets and screws. | 
To smooth everything out as well as stiffen it up, smear on some fiberglass reinforced body filler. All the gaps should be filled in when you're finished. | 
We'll also add the Rodz logo in the center of the piece. You can create your own logo, use a manufacturer logo or skip this part entirely. Cut out a piece of 11/42" MDF in the correct shape. Also, cut out a matching plate like those for the speaker rings. |
Again, make a bevel by routing with a 45-degree bit and create stilts with the tops cut at a 30-degree angle. Glue and nail the stilts and logo backing to the base. | 
The rear deck gets its flowing shape from fleece, which we'll stretch across the MDF base and stiffen up with resin. Before attaching the fleece, get out those plates for the speaker rings and logo. Pre-drill holes so you can match them up through the fleece later. When attaching fleece, start from the center and work your way out as you stretch the material tight. Staple it down securely on the underside. Here we placed the staples approximately 0.25" apart so that the material won't stretch. | 
Cover your pre-drilled plates with blue 3M masking tape and screw them to the rings underneath the fleece. Here is where pre-drilling comes in handy! |
Mix up some resin and apply it to the fabric. Be generous - soak the fabric about 95 percent through. | 
This is how it should look after you soak the fleece with resin. Let it cure overnight. | 
In order to smooth out all the rough stuff, sand the cured fleece with a 50-grit sanding disc in a die grinder. |
Remove the plates and cut out the fleece in the mounting rings. Continue to sand around the cutouts before moving to a 200-grit sanding disc. We need to get the fleece as smooth as possible, because even small imperfections will show through the vinyl. | 
Spray upholstery glue over the fleece and smooth on the vinyl. As with the fleece, start in the center and work your way to the sides, stretching just a little bit. | 
Now, break out the heat gun. You'll need to warm the vinyl in order to smoothly pull it over the sharp edges. Heat it just enough so it's pliable, especially when you're working on the corners, but don't make it so hot that it melts. |
Staple around it on the underside as you did with the fleece. When you're finished, all the vinyl should be completely glued down. | 
Now cut out the holes in the speaker rings and test fit the speakers. Pre-drill the MDF when mounting them. You can also now attach your logo. Our logo was water jet cut from 11/416" polished stainless steel. It's glued on with epoxy. | 
Your last step is attaching the rear deck to the vehicle. In the front, screws hold it in the corners, while aftermarket brackets fasten it in the rear. Now try it out in your ride. |