Alright, this jig I made to hold the dremel flex shaft horizontally worked *beautifully*. I hand-programmed the gcode, and I obviously have some more fine tuning to do, but overall, I’m on the right track!
Here’s the nice clean hole the jig produced. Adjustments required, but almost there.
Here’s the jig that’s holding the case down.
Video of the jig in action: