Rotational Pen

myminifactory

Just assemble it if you have a spring and a ballpoint that's 10cm long. Print each file and give it a shot. This rotational pen design is meant to be functional, with the ability to rotate one tip by about 90 degrees while holding onto the other end - allowing the ballpoint to move freely. Don't worry too much about the extra feature at the top; it's just supposed to revolve on its own and doesn't really do anything useful. Print it out, and make sure there's a gap of 0.1mm for good measure.