This is a 2" round hole 38x21mm rectangular switch insert with #4 FH, beveled screw holes top and bottom for mounting. Because square and rectangular holes are hard to drill I made a nice simple holder to fit a 2" round hole. 2" hole saws are easy to find and come with most doorknob mounting kits. The 38x21mm hole can be changed to suit your application. This Insert can be used with Speakers, Automotive, 12v Campers, and RV Lighting.
iPRINT 3D, HATCHBOX, Tianse, etc. PLA, PVC, PETG
Black or what ever suits.
I used PLA with an extruder temp at 220ºC, bed temp at 45ºC, and fan at 32% after the bottom layers are printed. I set the FR to 50-64% for the bottom layers too, to keep the small holes clean.