I needed a switch for the LED modules I mounted: https://www.thingiverse.com/thing:2881819
After looking, I remixed mimmim's (https://www.thingiverse.com/thing:2479455) single toggle switch housing to accommodate a round 20mm-holed illuminated 12v switch that pushes in from the front.
Raised the height of the case, shortened the length of the case. I left the depth as is, so the contacts are not exposed at the back, so the depth of the case remains 30mm - it will overhang the 2020 extrusion slightly, or you can offset the screw holes if you want it flush with the front of the 2020 extrusion. The switch hole size was also increased to 20mm.
Printed with the front of the housing on the build plate No support needed.
I purposely did not include a mount hole on the side of the case - initially I was just going to run the wiring down the frame, but found a 2.1mm panel mount female plug socket and decided to use it - I'd already printed the part, so I just drilled a 4mm hole in the left side of the case to mount it; the male 2.1mm power socket plugs straight in.
As the switch is illuminated, you need to use all three contacts (2x silver and 1x gold) - see the included wiring diagram for reference. The switch should be orientated so that the gold contact is att he bottom of the housing - I then mounted the side panel mount socket so that the longer contact was towards the bottom gold contact of the switch, bending it carefully downward a bit with long nosed pliers.
I wired as follows, due to the space available inside the printed housing:
1. "+" of the panel mount socket (short one is positive) soldered to the middle silver contact of the switch.
2. "-" of the panel mount socket (long one is negative) soldered to the bottom gold contact of the switch.
3. "-" of the LED light module soldered to the bottom gold contact of the switch.
4. "+" of the LED light module soldered to the top silver contact of the switch.
The SKP file is also included, if you wish to change the holes, etc.
Turned out well and works great.