A small update, because it seems ppl like photos.
I made wooden knobs
Next I built a dodgy control box to house all of the electronics, and switches, and a pi zero W.
I made it so that there is two power leads, one to power the control box, and the other is an out with a female socket to act as a controllable power source for the router or for a laser or something else eventually.
The two light switches control the output power lead, mains turns it on/off, and manual/relay toggle between directly on, or relay controlled via a 12v 240v/10a relay that’s connected to D9/Fan on the ramps board, so the router can turn on and off as the job executes with a ‘M106 S255/S0’.
The white round button is on top of the LCD kill button, which turns out is using PIN 41 in the Marlin firmware, and I could change that to not kill the job, but to reset the origin by sending a ‘G92 X0 Y0 Z0’ and navigating back to the status screen any time it is pressed whilst a job is not in progress.
I added an emergency stop switch, that I built into an extension cable I made.
So it can be used for other purposes if need be.
Inside the box is a Pi Zero W as well, powered off of the 12v/5a power supply that is powering the arduino/RAMPS board, running a nightly build of OctoPi, and its connected to the arduino/RAMPS via USB externally to the box as seen above.
The USB cable might seem weird, but it enables me to plug either device into a PC if need be to flash them. You can also not use the Pi this way and go back to repetier host or something similar.
Wiring it this way and driving it from the Pi means the emergency stop switch kills everything, no laptop holding stepper drivers locked, switch kills everything.