Check this out: https://www.youtube.com/watch?v=ic9dLWOwyYM
These spool winders look a lot easier to make than the older versions... the spring is entirely printed, as well. Needs eight M3x8 screws, eight M3 nuts and four 08 skate bearings... everything else is printed.
https://www.printables.com/model/292276-auto-rewind-spool-holder-for-reprack
Bill
I am using 4 of these Filamentalist spool winders. They work without any problems with the 3D Chameleon and they are quite easy to build:
https://github.com/Enraged-Rabbit-Community/ERCF_v2/tree/master/Recommended_Options/Filamentalist_Rewinder
I printed all the parts and did buy the rest at aliexpress. Shipment took only 10 days.