Polish Lego builder Paul “Sarial” Kmiec built this fantastic robotic arm using Technic Power Functions elements combined with an external pneumatic compressor!

Just another weekend build – this is basically a late realization of an idea I had back when I was a kid. The goal was to build a model of an entire human arm, with palm included, that would have as much realistic functions as possible while being of more or less accurate size. The look of the arm was considered insignificant.

The most complex part of the arm is obviously the palm with 4 fingers and a thumb. The thumb can be bent and raised/lowered, whereas the remaining 4 fingers have two joints in each of them. The index finger was operated independently, and it was fairly possible to operate every finger individually, except that it would take two times more pneumatic hoses, which were already quite numerous (8 of these was going through the arm). The palm can be theoretically rotated through full 360 degrees, but I never actually tried it for the sake of the hoses in the wrist. The whole arm was heavy and a bending under its weight a bit, but it worked well. I think it was pretty satisfactory for something that was built in just two days.