I'm gratified to find such a useful forum and to join. Briefly, I have several projects lined up and my current, um, focus is these mirrors (making them into telescopes will come a bit later):
1. A 6-inch f8 I started at the 2006 Delmarva workshop. It is polished out, but I had to leave the workshop before getting it fully figured.
Three mirrors from telescopes sold to me fairly cheap by a retired acquaintance:
2. 6-inch f/7, came with a home-made Dob tube but no base
3. 7-inch f/10, ditto
4. 12.5-inch about f/5 in a home-built truss Dob. Very rickety and out-of-line the one time I tried looking through it so I don't know how good the figure might be.
5. A mirror and mount from a 10-inch about f/6 that someone gave decades ago to the university where I teach science. The mirror was stripped at some point but has unknown figure. A very heavy steel OTA also, but I'm leaning to making this into a lighter Dob (no sign of the original GEM). This looks like it could have been a commercially made scope.
I've just finished making a tester and mirror stand from the plans on the Stellafane page, and I can see figures of some sort! (both Foucault and Ronchi) So far I've only set up and looked at the three smaller mirrors. All five are polished out, numbers 2-4 have degraded coatings that likely need to be removed and redone. So I have plenty to do but this summer and fall I have more time than usual to tackle it all. The first one at least needs figuring. I don't know about the others yet, but that is what the tester is for.
I'll post specific questions separately, but want to say thank you for all the good info I've already found here.