Engraving or Milling Attachment for 3D printer

This is an engraver attachment for one of my 3D printers. While it is not likely that it will be directly usable on other printers, it should be able to be modified for other devices. The engraver works wall and can be seen in action on https://www.youtube.com/watch?v=Jz5oezLPVYU
This device is suitable for engraving things like PCBs, signs etc and also for engraving although limited as to depth of engraving. It can also be used a a batch drilling machine for PCBs and similar projects.
As most 3D printers have open mechanical works a vacuum nozzle has been included to keep the swarf from doing any damage.
There are instructions for assembly, drawings and a parts list in the thing Files