CNC Etch-A-Sketch! Probably as good a project as any to get a handle on the basics. Very basics.

Tentatively, the big picture is this:

Part 1: CNC hardware / electronics / wiring
Part 2: Software, setup and calibration    • Build Your Own CNC! (Part 2) - Inputs...  
Part 3: Machine Design

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Music:
"Sally Goodin" & "Reuben's Train" - Nat Keefe with The Bow Ties