Wool winder / spool

A major disadvantage of buying knitting wool from dope-headed hippies is the fact that it doesn't come in ready to use form. It has to be pre-washed, color-fixated and -last but not least- wound up onto spools or into the familiar playthings of the common household cat.
In order to save my son from being used as a living wool-holder by his knitting-crazy mother, I designed this thing.
Design was by myself, although I frankensteined parts from other things into it:

http://www.thingiverse.com/thing:1832235
From this one I used the rollers as a mount for the skateboard bearings.

https://www.thingiverse.com/thing:1959208
Here I used screw and screw hole of the back plate for the table mount.

Design principle is a scissor-extender on two movable mounting plates. Two, because I was too lazy to design a fix for one of them. Some fixation for the mounting plates is provided by the friction between the bearings and the aluminium rod. Important ! The aluminium rod has to be of the anodized (matte) type to fit into the holes of the bearings and provide the necessary friction !
The whole device is to be mounted on the edge of a table w/ a max thickness of 30mm (less if you want to use a rubber protector on the mount). The rod will extend horizontally from the table. However, I found this to be a bit clumsy/unstable, so I will design a vertical mount later on.

On printing: 50% is probably too much for most of the parts. However, the table mount NEEDS AT LEAST 50%. 70% is better. Ah, and use PETG for the table mount because PLA is not flexible enough.

BoM (printed):
2 Mounting Plates
Rod protector knob
Table mount
Screw
Mounting bracket
8 scissor parts w/ thick end
Thin scissor parts (count depends on desired extension)

BoM (other):
2 608 Skateboard Bearings
8mm anodized aluminium rod
M3x10 screws (lots of 'em)
M3 Nylock nuts (again: lots of 'em)
M3 screws (I think it was 16 or 18mm), new version uses 20mm
M3 Nuts

UPDATE !
I changed the design for the table mount from a horizontal rod position to a vertical one. Just choose the variant you desire.

Hint:
The plastic screw has a really tight fit. Scaling the width and height (NOT the length) of this to 99% improves usability a lot.