Propeller

Propeller is a puzzle by the infamous "Roger D".  Roger D is a mysterious puzzle designer from Germany, and his actual identity is known only to a few. Roger is known throughout the puzzling world for his extremely difficult and high quality machined aluminum puzzles. Roger's puzzles are produced in relatively small numbers and are highly collectible, they are also sold with no information as to the objective of the puzzles and this is classed as adding an extra degree of difficulty to them.

This small puzzle is made of aluminum.  It has three hex nuts and the letters "R" and "D" are inscribed with a directional arrow on the front.  To solve this puzzle you must figure out how to spin the propeller.  Upon first inspection, it doesn't seem to move at all.  A difficult and creative solution to an amazing and collectible puzzle gem.