I am finally done with the arm.
All fingers work and the dome lights up. I had another set of lights in the control panel, but the battery kept opening my compartment-so I nixed that. We also have photos at the event-I just have to download them....later.
The majority of the arm is paper with a cardboard inner structure. Rubber bands are in the pistons and dental floss is used to control the fingers. The tubing, air regulators and gauges are real (and pretty heavy). Velcro was used to keep it on my arm. I will have photos of the wedding out soon-with me in full costume (and some other participants.