I was looking for expandable spool roller system but i didn't find any that i liked so i made new.

The idea here is to be able to expand as much as you want
 

I printed mine with PLA 0.2mm layer.
The pin that holds the bearing in place I made with cylinders in Prusa slicer. but you could use anything really. 

When i find time ill adjust this and add a pin that i like (not that happy with the current one but it works).

Update:

Added stl file for a pin im fairly happy with. printed it in PLA but i think petg would be better since it isnt as brittle and stiff.