A holder for toilet paper that fits onto a towel radiator. The same idea as Chris' https://www.printables.com/prints/61636-toilet-paper-holder-for-towel-radiator. The Holder snaps in between two bars of the radiator. The bars are 22 mm in diameter and the clearance between them is 145.5 mm. Hope it fits for your radiator, too.
The author remixed this model.