Simple spool holder with adjusting knob for different spools. It can be used for 250g, 300g, 500g, 750g, 1kg or bigger spools up to 105mm wide spools.

All parts printed out with Filaplast matt anthracite and matt violet PETG.

0,2mm layer hight should work just fine. Some parts needs to be rotated. For reference check print screen of slicer.

there are two options to print, only two parts are different, because I used two different screws for assembly. one is stock screw road that has hole for M6 screw and new one with hole for M3 screw, same goes rear part of holder. In case using original design, you will need one M6x15 ISO 7380 or DIN 912 screw with M6 washer and one M3x12 DIN 912 screw for knob. If you are printing parts with name Spool_holder_2_3mm_V1 and Thread_rod_3mm_V1, then you will need only two M3x12mm DIN 912 screws. Bearings are stock 608ZZ that come with original Prusa mini or clone kit. To finish spool holder 

Post-Printing

First remove support from Thread_rod_V1 and cut extra plastic on cylinder to get round shape so it will fit inside hole on Spool_holder_1_V1, if needed, use sand paper to get smooth surface for better fitting with part 1.

Attach bearings on parts Spool_holder_1_V1 and Spool_holder_3_V1. If they don't fit tight, use some CA glue to secure them.

Cut 2 110mm long aluminium square tubes 10x10x1mm ( use anodised tubes)
attach tubes to  and Spool_holder_2_V1. they should fit very tight, if not, use some glue (CA or epoxi).

Screw together Spool_holder_3_V1 and Thread_rod_V1. At first fitting will be very tight, so carefully turn screw all the way few times until it doesn't start turning with minimal friction.

Assemble together Spool_holder_1_V1, Thread_rod_V1  and Knob_V1 together and use M3x12mm screw to secure knob in place. Then just put all together and secure thread on rear end with M6x15mm screw (or M3x12 in case printing parts with 3mm hole).

At the end glue on bottom of holder 4 pieces of  8 x 2.5 mm Self Adhesive Hemisphere Silicone Rubber Cabinet Bumpers https://www.aliexpress.com/item/33024350570.html?spm=a2g0o.order_list.order_list_main.19.59821802GcQTOu

EDIT: Added bearing adaptor file for extra small spools. It is optional part, if needed, print that part 4x.