I am renovationg and existing shower and need to build a shower base. The dimensions are not standard so a commercial base does not seem to be a very viable option. I am looking for advice on design and construction as well as suggestions about materials. I am planning to use tile board on the walls. The size of the opening is 29.5 X 30.5 and there existing finished walls. There is an inexpensive metal shower stall in place at the moment.