Oke i hate these shower curtain things because after i while they tend to get loose an so you keep pushing them up until you are fed up with it and buy a new one.
Why do they get loose ? Well the design is wrong (maybe). If you jam them in the pipe the force will fade away after a while.
So i made these, they will apply the force from inside out, when the turn the bold the fastener will get pulled in pressing the split up tube part into the wall of the pipe.
I hope this will work better than the ikea one ;-)
printing the conner (bend pieces) is a bit tricky i tried bend.stl en bend2.stl both need support but both work. but i think version3 (to be made) (splitting the bend up in two parts) might be the best option for printing but then you would have to glue them together it could also do with a pair of wall mounts but i did not need then so feel free to make your own ;-)
The hole thing is made with parameters in mind, so it would work with different pipe diameters.
Mine where
outerDiameterPipe = 30
innerDiameterPipe = 26.5
innerRadiusBend = 10
I don't know if anyone needs these but he the world is a big place

Just make one
Print one set of fastner2xv3.stl
Print bend.stl or bend2.stl (both with exterior support)
Use a M3 40 mm bolt and nut and bolt the thing together but don't overdo it it still has to fit to pipe
Insert it into te pipe and tighten the bolt some more it will now lock into place.
Do the same on the other end
Make a mod
Goto
https://github.com/elmom/MCAD
Download
https://github.com/elmom/MCAD/blob/master/metric_fastners.scad
Open
shower_curtains_pipe fastener.scad and change settings