It's a silly little model but in case it'll help someone, here it is.

We bough an IKEA AVESJÖN shower curtain tension rod. It will not keep enough tension and just keeps falling so I designed this little thing to put underneath and hold it.

Printed with 3 perimeters and 30% infill. I used some 3M VHB to attach it to the tile and it's been holding strong for about 2 years.