Paper Towel roll holder for 3/4" wire shelf

I printed NotLikeALeafOnTheWind's version before realizing that I did not have 1" shelving!  Mine was 3/4 inch.  I printed an adapter to accommodate the smaller size but the bottom arm would droop somewhat.  I also experimented splitting the barrels ("knobs") that sit inside each end of the towel tube into two pieces to adapt better to tightening forces that would prevent it from inadvertently unscrew during use.  These STLs are provided in case they serve your purposes.

Ultimately, I scaled down the original and padded the clip feature to be 2mm thick, which provides a good connection to the shelving.  Since the paper towel rolls we have are not extremely bulky, the shorter reach of the arms isn't a problem.  I have embossed an arrow near the threads to indicate their direction.  If you then print a pair of regular and mirrored versions for top and bottom and orient them such that any friction of pulling the roll will act to tighten each side.

Scaled down the original model 75% but preserved thickness of the clip and internal rib features to guarantee a solid grip.  Added a mirrored version and embossed arrow to indicate direction of threaded features.  Knob piece with threaded parts has improved overhangs.