3D printing was invented in the late 1980s, and since patents are only around ... [Ethan]’s test bench consists of a Commodore PET Model 8032, running a 1MHz 6502, sporting 32k of RAM, and ...
Feedstock is supplied in filament form — aka wire — and melted to deposit on the work piece in order to build up either welds in the case of the welder, or 3D objects in the case of the printer.
It doesn't even use a smaller model of Pi like a Raspberry Pi Zero 2W ... available over at Printables for anyone to download and 3D print at home. Software-wise, the sky really is the limit.