The original hardware was held on by a tiny set screw (see last picture) and it just was not doing its job, so I made a sturdier mounting system, re-using the original bar and bar holders.
Printed in PLA, print 2 of each file. No supports needed if the towel_bar_holder_cover.stl is printed on its “back”. I used the screws that came with the original.
The author marked this model as their own original creation.