I only found one model on thingiverse by Lenry. Didn't like the fit and finish and was only 90mm. (https://www.thingiverse.com/thing:228267) I took his design and made it better for my use which is becoming more common in the USA. 

PRINTING

I printed in pla with 20% infill could go less or more not super important. the rollers I print upright with brim and support no problem. Bit of light sanding on the pin touching the build plate, cause of left over brim and mild elephant foot. But shouldn't be too much issue with well leveled printer. the rollers are a bit of a tight squeeze to get into place but worked fine for me. the belt for the rollers can be as fancy or simple as you want to go. I used the label off a soda bottle and works well. As for the size the belt you will have to figure out. there's no good answer it depend on the size roll you want. YouTube is your friend if you want to se how it works.