SummitFever
Eats Squid
I think there's a lot you can do with such machines in materials like soft plastic and wood but they will have trouble with harder engineering plastics (even acryllic/perspex) and certainly alu. Sure, there's plenty of youtube vids of people cutting alu on sub $1000 CNC machines but if the dimensions are not what's intended and the surface finish is terrible then it's not really 'machining'.awesome. there is a Open Source Mechatronics CNC Mill in my future. https://www.makerstore.com.au/product/kit-cbeam-machine/
DIY synthetic granite machine or mill CNC conversion would be the go. To reliably cut alu without hand-holding, flood coolant is really essential so design/build/buy a machine around being able to run flood coolant. If you can't reliably clear the chips and keep the cutters cool then you're pretty much stuck holding the machine's hand while it does its thing and that sort of defeats the whole purpose of a having a personal robot do your dirty work.