Home made ballpoint pen
I used a Pilot G2 refill for this pen, but the rest was made from stuff I had lying around.
The refill is retractable via the cam on the end. I can play with it for hours.
Here’s an exploded view, so you can make your own:
The shaft has two different finishes: I polished the grip part, and left the rest with the satiny finish left by the lathe.