My Final Project this semester for school. The full size replica was only released in Japan and was loco expensive, so I decided I'd just make my own. I made a few of the parts on a CNC machine, but I could just have easily printed and then sanded them as well. I'm currently waiting on the hardware to put the full thing together, but it all works, and moves. You will need a drill and a set of files (I'd recommend quality jewelers files) if you want it to be a finished replica like mine. I'm sadly missing a few of the updated parts on my school computer which I wont be able to get to until the end of January. Regardless here are the files I drew up and I hope you can print one and enjoy TBB's arm on your desk as much as I will.
Also: I'm listing it as a work in progress as I still need to create STL's for the knuckle covers and arm sleave (good luck printing those), feel free to remind me if I forgot to upload a piece or two, and have a great day.