>>105711036
I have a prusa i3 mk3 bedslinger, it's not the latest greatest but it has been reliable for years and of occasional use. I have an amateur racecar that I sometimes need to fabricate parts for, a 3D printer is useful for
1) actually making parts if it's small and plastic is fine
2) seeing if a part I designed will fit before making it from more expensive materials
3) making jigs to hold materials so I can weld/drill holes accurately

I also used to make guns from cold war era demilled parts kits and it was useful on many occasions there as well. I don't really care for the printed printed guns thing, but again, using the printer to make jigs and such. The CETME receiver bending hydraulic press jigs cost more than the whole damn parts kit if you have to buy them.