Continuing with my theme of not wanting to add extra t-nuts, this is my mount for a standard power socket as found on most atx psus. It does not have a switch, since I want that mounted at the front of my printer. The safety cover glues onto the back if your power socket is not protected by heatshrink or other insulation.

Print two of the parts. Break off the included support, and tidy up any rough parts that won't fit into the extrusion.

Put the parts in place into the extrusion (you have to put one in, then the other a few cm apart, then slide them together)

Put the power socket in, and bolt through the printed parts with m3 bolts. These push the plastic parts slightly apart, so there is a bit more friction and the socket will not slide along the extrusion.