I started by making a rough template/mold... Whatever, with some crappy foam from walmart.

Then, I sanded that down into the approximate size and shape I was looking for.

Then (and I didn't take any pictures of this) I covered the mold with blue painters tape and coated the entire surface with plenty of turtle wax. Only thing I had for a release agent. Before I go any further, let me just say that this is not my own idea. I got the idea from a video of a guy making a one off cafe seat. Ok, so, after coating all of the tape with wax, I laid down some resin, fiberglass on top of that, another layer of resin and so on. Three sheets of glass and it's pretty stiff. You can see that some of the tape is still stuck to the inside. This was after 2 sheets. Just checking the fit. You can see some air bubbles in the back part. I screwed that part up/ But before doing the third layer of glass, I pulled those two pieces apart a little, and filled the gap with some resin, mixed pretty hot. It filled in nicely.

Anyway, just thought I'd share. It's out in the garage with a layer of body filler on it. I'll probably let it sit til tomorrow before I start sanding. I'll post some more pics as it progresses.