A small keychain with rotateable gears.
Two versions: a square version and a zigzag version
How to make: see instructions
Edit: added a version with smaller clearances and added also the SolidWorks files

Step 1) Print 3 gears
Step 2) Print the holder and the dummy at same time
Step 3) Pause the 3D-printer when the printhead is located at the dummy and just before the bridge structure of the holder is going to be printed
Step 4) Place the gears ( make sure that the dummy s located far enough of the holder so that you can place the gears)
Step 5) Continue the print
Step 6) Your keychain is ready
( I have printed it with a prusa i3 / layer height: 0.2mm / 0.5 mm nozzle)