CNC stop button?
Need a big red stop button with a USB cable for your home built CNC machine? Perhaps this one from I Want One of Those would be appropriate?
You would of course need to remove the cover and modify the functionality so that it could provide an input to your CNC code but there’s a few experts on the web who have already hacked the USB Panic button for you.
Here’s some possibly more useful links:
IPac USB Switch interface (keyboard emulation)
Maxim instructions on adding USB support “anything”
Universal Pannel for CNC complete with stop switch, to interface with the Mach3 CNC software