For the bed of the machine i just used a 1/2″ steel plate. I went with hot rolled as they didn’t have cold rolled available. This was an eehhhhhh sort of choice. Its not dimensionally flat across the work area, and I really don’t have the power available to mill it directly. For the interim i attached a 1/4″ aluminum sacrificial bed on top of the plate which i could mill flat.
This gets us to the end of the physical construction. Final touch was drawer fronts, with some wrenches i got from my dad when he retired his mechanics business.