Parametric Sockets, can be built in either Metric or Imperial units. Also has options for either a straight or tapered socket.

I've included STLs for standard sets in both metric and imperial for 1/2 in drive and 3/8 drive. Metric set includes: 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 Imperial set includes: 5/16, 11/32, 3/8, 7/16, 1/2, 9/16, 5/8, 11/16, 3/4, 13/16

Update: Added double-hex sockets

Update: sizes may be incorrect. Project no longer maintained