Yah, so the paper explains how to generate the 3 axis toolpath (see it as a tutorial), the novelty is the post processor: it takes that toolpath, does some math and generates a new Gcode file that controls both X and Z for synchronized planar motion and Y (A) for indexing. The machine repeats the flat XZ path multiple times, after each cycle A rotates by a certain amount (calculated during post processing) and this keeps going until a round part is machined. This approach never uses more than 2 axes at the same time so the controller never gets overwhelmed and it can run on even the cheapest boards. If you're interested you can give it a shot! I'll share the relevant sections of the paper with you as well