As long as a bathroom can fit a shower that is at least 30 inches square and has enough headroom in the intended building space, it can usually be equipped with a shower enclosure. The finished shower may have some irregular angles or a ceiling slope.
One idea is to tuck the shower into corner and slant one side to accommodate a bigger entryway and to avoid blocking a doorway. In the design world, this is called a neo-angle shower because one end is wider than the other and it has mismatched angles. As long as one end is between 30 and 36 inches wide, this design usually works in small bathrooms.
Attic bathrooms might be the biggest challenge, especially if the shower has to be tucked in under a sloping roof. The fixtures are put on the tall end, and if there is space, a bench on the other. The shower door may need to be custom designed because of the odd shape.
Another idea is to create built-in storage niches for soap, shampoo and other shower necessities. This recessed storage conserves space, giving the users more room to move. Fixtures can also be placed higher up to maximize space.