I upgrade to a 2nd z axis. No space for the original spool holder so I made this holder. The plan is to make it possible to change the top part and add different. I upload more parts soon.
If the parts do not fit, you have to sand down the parts.

Update: I add a new one, I use the old parts and bearings.

Update: I add a extender it's for spools with a diameter over 20cm.

You need each part twice and 4 M5 nuts and 4-8 M5 screws.

Update: The top hole is M6 (spool holder top 02).