Well HIPS is a material (high impact polystyrene) not a vendor, but T/MC is a vendor. AP is the usual recommendation for smaller troopers because the parts are smaller than what you'd find in FX, AM, or RT-Mod. If you look around *carefully* many of the armor vendors are members on the forum. If all else fails, just send one of the staff members a PM and they will point you in the right direction. It's a little bit of a game trying to decipher all the information I know, but necessary to keep the sellers protected, and to make sure people that join up on FISD are really interested in trooping with the legion, not just blowing in from anywhere and finding contact info for these important people that make the armor.
PM sent..