Yes, this looks like a great learning device! It could also be good for prototyping controls for a more serious tool, and the pen tool and maybe even a light e

Yes, this looks like a great learning device! It could also be good for prototyping controls for a more serious tool, and the pen tool and maybe even a light extrusion head might produce some good results. But cutting anything is, umm questionable. In general, a cantilevered configuration is inherently wobbly compared to a gantry configuration that rolls on parallel rails/beams at the outside of the workspace. Even a massive Bridgeport-style mill has issues vs a moderate gantry CNC mill (although uses a lot less shop floor space). All the force paths are working to bend the cantilever device, vs all the gantry geometry that works to minimize error. So, while it looks like a great effort and good for some things, if they want to offer any even slightly serious cutting capability, they'll need real work on the stiffness.