I don't have any photos to show my latest progress because I made quite a mess.
I cut slots for the fins in the bottom of the main tube and decided they weren't straight enough. So I went ahead and cut about 9" off the bottom to allow me to re-do the slots. It was while marking the tube for the new slots that I realized that I should have just enlarged the original slots instead of cutting the tube shorter. Oh, well, the shorter length will look better with the Titan-missile-like paint job and I think it'll still be stable without nose weight.
Anyway, the second time, I cut slightly wider (and straighter and neater) fin slots. I slid the fin can assembly into the tube with the fins in the slots and everything lined up well. I used wood glue to secure the assembly in place.
I used epoxy to seal the gaps between the fin slots and the wood braces holding the fins. After that dried, I filled the assembly with expanding foam. Here's where I really messed up. First of all, I'm sure I didn't really need the foam. Second of all, I made a hole in the top of the fin assembly for the foam and for running the wires from the timer to the outboard motor igniters. But I didn't make the hole large enough. When the foam expanded, it caused bulges in the body tube between the fins. And some of the foam found places to leak out of the bottom of the rocket.
I was able to clean the foam from the bottom using a Dremel, my fingers, wooden sticks, a razor knife, and quite a few cuss words.
As far as the bulges ... at first, I was going to leave it be and claim I planned it that way. But I realized I'd have to mount the rail buttons on stand-offs or a stringer to get over the bumps and that didn't appeal to me. And I finally decided that it just didn't look good.
So I spent a lot of time cutting the bottom of the tube from the bottom centering ring, pealing back the "flap" between the fins, scraping out foam, and clamping and gluing it back together. The bending of the body tube to get to the foam cracked the fiberglass in a few places, so I've got some things to fill and sand. But it really doesn't look so bad now. It's painful trying to fill and sand the cracked parts between the clear fins, but I'm working on it.
-- Roger