HI,
I bought a 3d printer some years ago, joined a forum, found that some the parts were lacking as they were made from perspex and mdf, took the design, converted it for laser cutting and had them made outside and sold to members, later on i made them myself by plasma cutting and hand finishing and now they are CNC milled and hand finished. Unfortunately practically every one of this model now has my parts on it
and sales have of course dried up.
Most of the newer printers have learned from these early ones and are now far better built. The Cetus printer even has linear rails !
Drones I know little of, will check that out.
My cabinet idea was maybe fully built, ready to connect supplied motors, 3 axis, 3 axis +slave or 4 axis options, ethernet connection, linear PSU, some flavour of motion controller. Something like that, lots of options but all with the idea of fit, connect and go. I have checked and they are of course already on eBay but using low cost parts, smaller motors etc - I want something that will last. Just ideas at present