I have included 2 types of key styles for this project the finished piece should hold 6 keys the shim is needed in the middle to prevent warping when the keys are being used.
You will need 3M bolts and nuts for this preferably locking nuts.
I used Simplify 3d as a slicer and made the wall thickness 4 layers to make the area around the loop where the ring goes through strong enough to last
This was printed in ABS. If you use a 100 watt light bulb in your print enclosure with a heated bed it will prevent warping
If you do this in ABS use a watercolor brush to paint acetone around the loop area this will help prevent delamination.