I want to use a portable foldable bathtub in my walk-in shower, but the shower's divider wall (2 inches tall; 4 inches wide) makes the tub unable to fit. What material could I use to build a frame, so that I have a flat surface across the shower's divider wall?

I have a shower setup similar to this one here.I want to use this bathtub in my shower, but unfortunately my shower floor (restricted by the divider wall) isn't wide enough to accommodate the tub's diameter (diameter of tub is ~2 inches too large).I want to make a support frame like this to create a flat surface across the divider wall, so that I can use the tub in my bathroom.-What's the best material to use for something like this? Wood would be the easiest for me, but I'm not sure how wood should be waterproofed for indoor use, or what kind of wood would be best.Any advice would be appreciated. Thank you! via /r/DIY https://ift.tt/2NCqg5O