Having a speed control for the wire feeder is looking promising.
The motor driver is not quite sorted out yet. The chip is overheating while the motor is stalling trying to push the wire and staying at ambient temperature. i.e. the system is not balanced. The same motor had enough power and ran at proper temp when driven by the TinyG board.
A tb6560 chip is the next experiment. It is a common part in many stepper drivers. There is a plethora of pre-made drivers with this chip so there is no reason for me to build a board from scratch.
The biggest cost is the time delay waiting for parts to arrive.
Using CAM software to create an additive tool path is working well for simple objects. The lines of code is about one tenth of a typical model slicer output. This is due to the fact this CAM software can write code for G03 output (circular interpretation). I haven't seen any of the 3D model slicers use this shortcut. A typical slicer cuts the model into a series of lines so something like a small circle can have a big bunch of line segments which can often be seen in how smooth the tool moves.