This adapter allows fitting a spool rewinder to the SV06 but because of the orientation of the original spring tension bit an clutch you need to flip the arm so the spool sits on the left hand side , still works with the original nut from the standard spool , i used some 8mm threaded rod and some nuts .

You will need :

The “modular spring stl files ” from the links below .

a length of 8mm rod and a couple of nuts 

there is also a locking nut hole on my model so you can add a M3 and nut to lock the shaft into the adapter to stop it spinning .

I worked this model in tinkercad to work with these models : 

Universal Auto-Rewind - SpringRound Modular by ra100 https://www.thingiverse.com/thing:4512055
 

Universal Auto-Rewind Spool Holder 

https://www.thingiverse.com/thing:3338467

printed in PETG

ENJOY.