Ah ha - okay, also found the threaded m4 10mm ball bearings.

okay under £5, altogether, for 12 threaded 10mm ball bearings and 12 magnetic cups :-)
Bought m4 bolts yesterday as i found some really cheap t-slot nuts with m4 thread.

Have to admit I like getting all these little packets from china.

Currently thinking about a volcano hotend with 3:1 gearing - like what autowhiz uses. Not cheap, but I'd like to use my little nema 14 motors. Haven't tried one yet, might not need gearing.
Struts should get here today.

So with threads balls and magnetic cups - should work really well.

that perspex on the carriages looks very thin and flexible. Is that a good idea ?