I laid down some resin, added the CF cloth, added a layer of waxed paper, and rolled out the excess resin with a roller tool. I didn't have a big enough piece to do the whole thing, so I had to make it out of two pieces. The seam ended up feathering out the individual carbon filament when I rolled it out. I don't really care because you won't see any of this when its on the car, and the entire point of this was to learn. I definitely learned.
Today I trimmed off the excess with a dremmel, sanded the edges smooth, and drilled the resin out of the screw holes.
Overall I'm pretty happy with it. Assuming it works of course. I still need to jack the car up and get the splitter back on, then see how it holds up.
Carbon fiber dust is fucking itchy. It's no different than fiberglass in that regard.
