I was reading up on the ITP C8 and noticed it was designed to mix match parts from the 1AA and 2AA models. Is there a website I could build one by just ordering the individual replacement parts?
Not that I know of. You use to be able to buy individual tubes so that if you had an iTP C8 you could get the tube for the C7 and vice-versa. The heads and tail-caps were interchangeable. These lights have been discontinued as far as I know and replaced with the SA series so they are going to be hard to find. They were somewhat modular like you say but I never saw any parts sold separately except the tubes.