a home made bathub? does the thought of a leak scare you? what about 10 years from now? 15 years?
i dont think youll find step by step instructions, so you have to follow the rough steps i shall give you
you would have to frame it out, rough the plumbing, put the shower pan material, then some chicken wire mesh, thin-set cement for general shape, then lay your tiles and grout, finish off the plumbing and hope your homemede tub dont leak or all your work is for nothing