Custom wallplate for three 12v outlets. I designed this for my popup camper - the one 12v outlet is positioned sticking right out into a high traffic area. I wanted to add an additional outlet and USB charger, and relocate it to an out of the way area. All of the 3 outlet packages I could find came with low output USB chargers, and were $25 - $30. I found a 2 pack of power outlets for $6 and a two port QC 3.0 USB charger for $15.

The openings are sized at 29mm, and fit the threaded 'barrel' of the outlets perfectly. I did not bother with adding the flats that some outlets have - the USB charger I purchased didn't have them. The inset ring is 37.5mm, and all 3 outlets fit perfectly. Screw holes have a 10mm inset to accommodate pan head screws.