I have seen mini-lathes for around £100 on Amazon and Ebay and would wonder if that would be a better investment as everyone seems to imply that the quality/toughness of 3D printed items (unless made on industrial printers) are poor. I know the R&D guys at the company for which I work are printing some pretty exotic materials but their printers are bespoke. Some of these lathes would allow for machining of metals in addition to HDPE or plastics, so could be used in other applications and larger robots too. Add a basic bench drill and you'd have a nice little workshop. Admittedly not as cool as 3D printing.

Just my two pence worth