It's pretty easy to accomplish the same using virtually any 3D printer, even something as simple as an Ender 3 can be set to pause at a set layer in GCODE where the filament can manually be changed to the next desired colour. Realistically, this is only practical for things like signage, where you start with the base colour (such as yellow or green) then switch to the next for text and details, and if done properly with compatible materials, can look incredibly well-done.

Yes. I'm looking for a Linux program that can turn SVG into signs like that (STL). Because doing it manually is a lot of work.

(Maybe it is easy to do in OpenSCAD?)