I made this to hold a set of 6 3/8" drive allen wrench sockets. Commercially available socket organizers had way too many slots for this six piece set.

Note: I've updated the design to include a customizable version.

Print flat side down. no support. For me, a raft helps, but is not necessary. I recommend PLA but any material should work. the sockets should have a slight clearance fit making them easy to insert and remove.