m16 studding work instead of ballscrews ?

[irving2008]

Also...those TR12 with the 3mm pitch - bet you can't roll your own nuts with them that easily ...which starts making them less attractive to someone like me (who's CNC kit budget is miniscule!)

Assuming you're using Delrin nuts, you make sure you have a 100mm more than you need, chuck it in the lathe (or a drill chuck), spin it up and file a taper on it for the last 20mm, then at the other end file some flats to hold it in a tap wrench. It'll work fine as a tap for delrin with a bit of lube and some muscle....

Or find someone who has the relevant tap and borrow it...