I've been thinking about how I want to build the fiberglass engine enclosure. I want to make it slick-finished glass like it came out of a factory mold, but I want to shortcut the process by skipping the plug stage. I just want to build a single-use mold with a smooth-surface material. Something like you would use in a a shower.
Maybe a sheet of powder-coated aluminum like I built my camper out of; I could roll curves into that. That stuff's not cheap, but might be worth $75 to build a nice mold with only one seam around the top.. Now that I think about it, aluminum is probably not much more costly than that shower board, and much easier to curve.
I have a good idea of how to brace it on the outside by using adhesive to attach the bracing to the sheeting.
I think the top could be flat, and I could form smooth fillets with caulk.
Anyway, the wheels are turning and the vision is starting to come to me.