My thought on it was that casting the Hasbro head might be better than the Tomy one, since the bit of shrinkage will only help the Hasbro helm. Plus like he said the Tomy helm is multiple pieces and I would guess the back of the helm, because of the shape might be a hassle to cast right every time so both pieces work together well, but I know jack about that side of things. lol
I also think that it might be a good idea to make the head an optional piece since there are likely gonna be people with Tomy helms they intent to use. So likely not as many heads would be cast compared to every thing else.
So the parts needed are.
Casted:
Helmet
Chest
Back
Elbow armor
Bicep armor
Shoulder armor....I figured you probably would like to do proper ones.
Sewn:
Cummerbund & pouches
Bodysuit
Neck cover
Other:
Rubber belt: The rubber belt thing I would like to find a better way of making because it needs to be flexible so i don't know if that will be able to be cast, or at least worth while to cast. I would like to see the pieces that are on the belt cast then attached to real straps. I have thought about just doing the casting for those little bits myself then I can slap them right on belts. They seem like simple little bits to cast for a person like me, with only a little bit of casting experience.
leg Holster: This would be easy for me to make and don't know why I have it here, except that its similar to the rubbery belt and a funky shape so likely not castable.
Stuff people would need to get themselves:
Boots
Gloves.....unless you wanted to cast these.
Nude Dollie
Anyhow I think that's everything.