My Plan

Ideally, I would like to drive this thing from an Arduino UNO running GRBL so I can get a lightweight, low cost solution that I can plug into a USB port on a laptop or Mac. I know only a little to start with on grbl - but my understanding is that it is a g-code interpreter running on the Arduino, and doesn’t need a lot on the PC driving it.

I know that in most cases, I’d be designing my things in a CAD app, translating to STL, then to gCode, and this would apply on the Mach3 + windows, LinuxCNC or GRBL route.

My understanding so far on the Mach3 setup is that it would need a dedicated computer with parallel ports that is not allowed to run other apps at the same time. LinuxCnC may be marginally better on performance in this way. Somehow - the Arduino version sounds tidier, and getting it working and well documented would lay down groundwork for others to follow.