Yes, they work really well on a simple CNC mill. Same "thing" as a 3D printer.
Design them to be milled, instead of cast or forged, and you can make one-offs all day long.

I feel i have mentioned them enough so that people get what i mean by 3D printer, but, i recognize that new readers would never see that.

Also i have been CNC milling parts for 30 years. And so, i think everyone knows about it and what it does, but the 3D router is still "new" to most people's minds.