We have five standard size shower pans: 3' x 3', 3' x 4', 3' x 5', 32" x 5', and 42" x 42" neoangle. These standard pans have a built in curb around the with a fixed drain location.  Custom pans can be made to for any other size showers.  The location of the drain can be moved and the threshold is a separate piece from the shower pan. 

This is a custom shower pan with a shelf and a bench.