I attempted to build one like it and found out the devil is in the details. Switch contacts that are reliable time after time. That is why I purchased the one that I just listed on Craigslist yesterday. It works like it should, but decided not to go the route I had intended when I first bought. Ended up just buying the 3D art I use with my router table.
Retired - Journeyman Refrigeration Pipefitter - Master Electrician - MakerGear M2 3D printer- 20 Watt Ray Fine Galvo fiber laser, 6 Watt blue laser engraver project