TUSH spool holder with planetary gear

Well, I needed a decent spool holder for a 2 kg spool badly, but the ball bearings shipment from China takes ages.

So I took k3xx's version of the spool holder and

* made the walls a little shorter so they would print more easily on a Cetus 180x180 mm² bed,
* replaced the the need for ball bearings and a bearing guide by a bearing with a guide using emmett's planetary gear [1],
* added a rim to the guide so I get it off the print bed in one piece,
* and a snap-in connection to the axes