Step 10: Arm Extensions
In this case, I needed to make giant hands and add an extra foot or so to the wearer's reach. To achieve this, I sculpted out a pair of palms using oil-based clay. Then I went ahead and sculpted individual knuckles for each of the hands using more clay as well as some wooden balls and scraps of PVC pipe I had laying around. Then I made a mold of each of the parts and rotocast them in urethane resin to make them hollow and lightweight.
Once I had castings lined up, it was just a matter of choosing a gesture* and gluing the finger pieces into place on the palms. For the hands that would be holding weapons, I had to build the fingers around the grips. The assembled hands were then glued onto the end of a piece of 4" ABS drain pipe with a handle inside. The pipe would slide over the wearer's arm inside the costume's forearm and act as a sort of brace to help the wearer wield the weapons and whatnot.
*It was very hard to maintain an adult level of maturity in this stage. If you ever stumble across photos of Space Marines flipping peace signs, giving people rabbit ears, or poking each other in the eyes 3 Stooges style, know that I faltered in a future build.