With gas prices rising and the economy tanking, maybe we all (that includes car audio enthusiasts) need to take some cost-cutting measures. I decided to take a car that had an install in it for years and update it. There's a lot of carbon fiber in the rest of the car, and I wanted to use carbon fiber in the sub box to match the theme. I also wanted this box to be as light as possible. I took a piece of 12-inch PVC left over from another project and decided to use that for the box shape. This enclosure is made from 6061 aluminum, carbon fiber, and a little epoxy to hold it all together.
Since I knew the radius of the PVC, the outer size was easy to figure out. I then drew up a few braces using a square, adjustable angle finder, and some Mobile Solutions templates. Once the final MDF brace template is done it can be transferred to aluminum on the router table. I'm lucky enough to work with someone who could transfer my design and CNC it, so they were all perfectly symmetrical.
For the face of the enclosure I used 1/4-inch 6061 and cut it on the table saw. I cut an angle on each side, as close as possible to the angle the carbon meets it. Two holes were rough-cut with a jigsaw for our Polk Audio MM1040 woofer. I then used an MDF template to cut perfect holes on the router table. A small landing arch (slightly smaller in diameter than the end cap) was glued to the end cap. This provides a spot for the carbon fiber to be glued to the aluminum.
Squares and clamps were used to ensure the end caps were straight. More clamps and pieces of MDF were used to attach the braces. A 1/2-inch square aluminum rod was glued to the back of the face for a spot to glue the carbon fiber. Duramix panel bonding epoxy was used for all aluminum/aluminum attachments.
Nineteen-ounce dry carbon fiber weave was taped to the PVC then wet-out with surfboard resin. A second and a third layer of 19-ounce carbon weave were added and wet-out as well. Multiple coats of resin were added on top of the third layer of carbon fiber to ensure a flat surface after sanding. A dual-action sander and a long board were used to sand the resin as flat as possible.
1 and 2. Since I knew the radius of the PVC, the outer size was easy to figure out. I then drew up a few braces using a square, adjustable angle finder, and some Mobile Solutions templates. Once the final MDF brace template is done it can be transferred to aluminum on the router table. I'm lucky enough to work with someone who could transfer my design and CNC it, so they were all perfectly symmetrical. | 
3. For the face of the enclosure I used 1/4-inch 6061 and cut it on the table saw. I cut an angle on each side, as close as possible to the angle the carbon meets it. | 
4. Two holes were rough-cut with a jigsaw for our Polk Audio MM1040 woofer. I then used an MDF template to cut perfect holes on the router table. |
5. A small landing arch (slightly smaller in diameter than the end cap) was glued to the end cap. This provides a spot for the carbon fiber to be glued to the aluminum. | 
6. Squares and clamps were used to ensure the end caps were straight. | 
7. More clamps and pieces of MDF were used to attach the braces. |
8. A 1/2-inch square aluminum rod was glued to the back of the face for a spot to glue the carbon fiber. Duramix panel bonding epoxy was used for all aluminum/aluminum attachments. | 
9. Nineteen-ounce dry carbon fiber weave was taped to the PVC then wet-out with surfboard resin. A second and a third layer of 19-ounce carbon weave were added and wet-out as well. | 
10. Multiple coats of resin were added on top of the third layer of carbon fiber to ensure a flat surface after sanding. |
11. A dual-action sander and a long board were used to sand the resin as flat as possible. | | |