Greg's X-Carriage with Kühling's LM Holder - inside facing nut traps on bearing holders

TommyC's fine design, with a small change for accessibility. I reversed the trapped nuts one side (so that they are inside rather than out... as requested by RustyPaint. An excellent idea, I might add.

UPDATE: new part, there were some shape errors that are now fixed. Also added my modified SCAD libs that required tweaking to flip the holders.