These are clips that slot into MasterForce rack shelving uprights. These are sold at Menards and other big box stores.
This particular clip is set up for a power strip with a screw pattern of 1.125" x 4" and uses #4 screws. The hole spacing on the rack is 1.5" so you use one row of screw holes on one bracket and the opposite ones on the second bracket. Attach bracket to power strip then press it into the holes on the frame and slide down to lock.
Printing
Material: PETG
Orientation: Print so layer lines go though clip arm. (you will need supports for the clip)
Infill: 15%
supports: bed only
FreeCAD 0.21.1 files included.
The author marked this model as their own original creation.