Tinik spool rewinder

I got a little tired of the buffer system that came with my MMU2 so I decided to make something that would suit my needs better. 
Initially I used printed springs from PLA, but they didn't last very long and would not work at all in a heated enclosure.
This version uses a steel spring found in these retractable tape measure devices:
https://www.amazon.co.uk/Hanyousheng-Measures-Measurement-Retractable-ScaleTape/dp/B097GDSPXK?ref_=ast_sto_dp
They are glued together so be careful when you pry them open so you don't hurt yourself or damage the spring.

The rewinder works more or less like any other spring loaded auto rewinder I have found except from the spiral in Part_6 which limits the number of turns to 2.4 with the intent to save the spring and allows for easy pretension during assembly.

Check all close assembled surfaces for smoothness and sand slightly if necessary. Usually the top surfaces after printing.
Take caution when assembling the steel pins so they don't protrudes too much. Especially the 2x9mm steel pin which must not touch the bottom of the spiral.

The center axle will need some modification to fit any other system.

The roll are 75mm in length and the diameter is 48mm

All dimensions are metric.

Parts per rewinder:
2 x 608 ball bearing. Must rotate freely! Degrease if necessary.
1 x m3 hex nut
1 x m3x12 socket head screw
1 x steel spring mentioned above
1 x steel pin 2x15.5mm
1 x steel pin 2x9mm

Print settings:
Layer height 0.2
Perimeters 5
Bottom solid layers 5
Top solid layers 5
Infill 30%

Support on Part_1 and Part_2 (bearing seat)

I should add that the side stop (Part_10) was printed with PETG in my system and may be too stiff if printed in e.g. PLA, especially with the specified print settings.