Version 3 is a major upgrade. I will be replacing the small rotary tool (Dremel like) with a much larger spin saw. The unit is being tested in this video:
The stepper is a modest size, 12V 36ohms which draws 0.33A per coil, 0.66A total. This is much bigger than the stepper on the previous version. I have vertical movement of 6 inch / minute before overdriving / chopping. So hopefully I can bump that up.