The included design is the one on the left in the pictures and is the 3rd revision. You will need to print 2 of them for a set.
This paper towel roll holder is sized for rolls up to about 130mm diameter (I sized it for viva giant rolls). The holders are simply taped (preferably using VHB or similar tape) to the desired surface. Use the rolls you will be using as a spacer to accurately space the holders. They can be mounted in many configurations; Under cabinet, on table top, on back wall or side wall (and if you really want at any arbitrary angle on a surface!).
Print 2 copies with at least 2 shells and at least 10% infill.
Apply double sided tape to the bases (a moderately thick VHB works great for this application and I found it adheres to PLA very nicely).
Remove tape backing from of the roll holders, insert into paper towel roll (as a spacer) and adhere to surface.
The holders can be flexed a bit to insert and remove rolls.
You will notice in the pictures the design changes from V2 to V3, Larger radius at the mounting to upright, and much shallower part that sticks into the roll.