All figures bodies are castings from an Amazo body. Green Lantern had some alterations done to the legs to give him some height, and Martian Manhunter had some build-up on his neck and shoulders, both done with Sculpy. The towels are all made of Sculpy. The heads were castings as well, as follows:

Batman: New Batman Adventures Undercover Bruce Wayne
Superman: JLU Superman
Green Lantern: JLU Green Lantern
Martian Manhunter: JL Martian Manhunter
Flash: JLU Elongated Man