Summary

Some simple screw-mounted wire clips to secure 2-strand 16 AWG wire commonly used in non-grounded extension cords (at least in the USA). I designed 3 varieties: a minimal clip using one screw to mount one wire, a two-screw clip to mount one wire, and a two-screw clip to mount two wires side-by-side.

These clips are designed around using #4 screws, which should also work well for 3mm screws. I had some bed adhesion problems with these little clips so I made a version of each design with a brim that doesn't fill in the interior of the clip (as a slicer-generated brim would). Also included are the .STEP and .f3d files for each design incase anyone would like to tinker with the design.

Supports are not needed. I recommend printing in PETG, ASA, or ABS. The clips will need to bend slightly to clip around the wire, and PLA is likely too brittle. Consider also the environment which the clips will be exposed to when choosing the appropriate material, specifically for temperature and UV resistance. 

This design was spurred on as I was upgrading my garage lighting and needed a way to organize and route the wires along the walls and ceiling. Why go to the hardware store when I can spend the same amount of time designing a custom solution?