Spool holder for shelf

English
I have searched and printed several spool holders, but no one has met my needs, these are my two proposal entirely printable without supports:

First (with bearings)
Pieces needed:
1 - n. 1 6 mm threaded bar;
2 - n. 5 M6 bolts (I attach the STL if you wanted to print it);
3 - n. 2 bearings with inner diameter 6 mm and external 20 mm (those commonly used in skateboards);
4 - n. 4 screws to fix the support to the shelf.

Roller diameter: 50 mm.
Everything else is printable.
Assembly is very simple, just look at the pictures.
Note: I have provided the bearings to reduce friction to the maximum.

Second (without bearings)
Realizing that the bearings almost never work, I made a roller without them, easier and faster. just slip the bobbin inside ;)
To reduce friction I have created "threads" in relief on the sliding wall of the spool.
To make this it just print the right roller (in addition to the support)
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