This, I think non-planar PCBs are an incredibly niche thing, and very rarely necessary. you can just run wires/connectors between multiple PCBs, it's no biggie if your prototype needs some manual assembly.

Fiber laser etching is the way to go, the required equipment is already below $2000, and the process is quite simple. Additionally manufacturing copper/aluminium is next to impossible at home, considering their melting points.

You could even use a pre-masked copper plate (which is less reflective than copper), so your PCB would come with a mask.