My wife and I recently bought a new home, and the shower in the master bath is a relatively tight stall shower. In order to fit a human body in there and still have access to all of the necessary items needed in a shower, we wanted to install corner-shaped bins into one of the corners of the shower, but without drilling holes in the tile. Suction cups to the rescue!
However, we discovered that our tile is not smooth enough to hold a suction cup for more than a few minutes, and our shelves were falling down.
I considered glue, double-sided tape, and sticking smooth-surfaced items (ie. cut glass or plastic) to the walls so the suction cups would hold.
But in the end, I hit on a simple solution that's been holding strong now for over a month.
Step 1: Try to Stick the Suction Cup
I'm working here with a smaller, hook-style suction cup.
The first step is, naturally, try to stick the suction cup right to the tile. If you can stick it and it doesn't pop right off when you pull on it, congratulations, you don't need this instructable.
On my tile, the suction cup pops right off with little or no force.