Riddle Me This Challenge Key

I made this key for my STEAM class where we are learning how to design for 3D printing. Our challenge was to find a riddle and create a 3D object that is the answer to the riddle we chose.

My riddle is: I turn once, what is out will not get in. I turn again, what is in will not get out. What am I?
Answer: A key.

This is my updated version of my original design.