I'm planning on making an open source 3D printable robot arm in the next year or so. I've made a good 3D printed remote control car that uses few external parts (no screws). Working on custom printable motors now and then I'll probably do an arm. Nothing to share yet, but if you want you can google my company (Flutter Wireless) and join our mailing list. I have a bunch of circuit board to deliver first but I will be focusing a lot on robotics as time permits.