I made this shower shelf floor (my shampoo and everything else always tips over because of the thin struts. I also installed small squares to drain water.

It is 200mm x 200mm x 3mm.

I printed this model the first time a little smaller just to test it, you can change the size of the shower shelf floor in the slicer depending on how long the sides of your shelf are.

Please have fun with it and share your results, also give me a like or follow me for more stuff :)