A few nice 3 axis milling machine images I found:
3-Axis CNCMilling Machine China Rail Guide 1
Image by r_william.king
These are the rail guides I used. I didn’t like the idea of metal on metal (potential wear fault) so instead I drilled into the plexiglass and used these small plastic wheels as rail guides. They are drilled to be on the exact outside of the rail, and hold the stages in position while still allowing movement.
3-Axis CNCMilling Machine China “Magic Bullet” 2
Image by r_william.king
On the other side, a copper thread which is 1/4 x 20 😉
3-Axis CNCMilling Machine China Motor Mount 5
Image by r_william.king
Another closeup.