If the helmets were based on the same design, it might be possible to make the face shield so that it can just be glued onto the helmet. I should think that a SST (Movie) style helmet should accomodate that fairly easily.
I believe that for the first spruce we should focus on one kind of helmet to increase the number of trooper we can get on a spruce.
I believe we should be aiming for 8 non-interchangeable or 6 interchangeable on a spruce.
The advantage, I see, of interchangeable is it might lead to more expansion spruces more quickly, assuming the sales are their. I also may lead to interchangablity with other spruces.
After rereading Wargames Factory I came to the realization that it was not the place to look for a small number of my specific troop (futuristic psychic frog-people, don't ask) because has high setup costs and I should be asking for troops that sell by the bucketful.
That said I am surprised at what is selling and what is not. I suppose that shows I have a lot to learn about the market.
I would have though the science fiction horde markets would be:
Generic Light Hard Plate Future Trooper - Halo, Star Wars, Star Ship trooper the Movie
Alien Xenomorphesc Bug-Lizards
Terminatoresc Skeletal Robots
Hulking Mutant -think Games Workshop Ork/Orc but maybe propertioned human heads, Mavel comics The Hulk
Some of these are proposals and they are not the ones that are coming out first. Again shows what I know.
A bit of a rambling post I think I will stop now.