Print in the orientation of the STL. There are built-in supports - these should break away after printing. If your slicer creates supports, you've done something wrong - turn them off!
This should be printed with the standard voron settings in ABS.
The switch should be orientated so the white retaining clip points towards the motor (away from the centre of the printer). There is a cutout on the back of the part that allows room for it to clip into place.
There are two locating pins on the front face of the skirt piece which will orient the cover vertically. Watch out not to snap these off - they are tiny, and only held on by layer adhesion!
There is an STL for a tool which makes tightening up the retaining nut much easier.
This can be wired however you want. Some ideas are:
I'm using this to power off the 24v PSU, which means I can use it to adjust wiring on my printer main board as a side-effect, while keeping the Pi on and booted. Saves me from shorting things out like an idiot.
It may be possible to put the whole printer (or at least 24v and heated bed) through the printer, but these estop switches have a lower current tolerance to the switch on the back of the printer, so may not be rated sufficiently.
The author remixed this model.