My 3D print is a plexor or more commonly known as a reflex hammer. I decided to do a plexor because astronauts lose fat and bone mass in space, about 1-2% in a month. Astronauts need to know how good or bad their reflexes are, because it will show them when they need to go back to Planet Earth. Yes it is true that some people did a plexor, but only mine works. My plexor has a semi-circular end. This is what a regular plexor has. My competition has a flat face which wouldn't work because a flat face wouldn’t make contact with the tendon beneath the kneecap, which causes the reflex. In conclusion only my plexor will work, and plexors are highly needed in space.