IKEA Gommaren Shower Curtain Rod Support
The IKEA Gommaren shower curtain rod is designed to be cantilevered but in reality it sags after time especially when heavier (read: better quality) shower curtains are used.
This design demonstrates that one corner can be propped up, lending support to the overall frame. I have a 1/2" wire trunking screwed to the wall as a support for Bygel containers as planters - not everything needs to be printed :-) so that trunk lends support.
My bathroom set up is probably unique but hopefully this gives you an idea if you are faced with a sagging Gommaren :)