Ralph Mowery wrote:

We had a local marble company do this for us. They come out and measuer the
size of the base, go to their shop and mix up and pour out what is needed.
This is sort of an epoxy type mix. They then bring out the coustom sized
base. We also had them do the walls of the shower for us. Then install a
glass door. The stepover is only 2 or 3 inches high. Just enough to keep
the water in the shower and off the floor. As we have another full bath, we
can take a tub soaking if we want to.

Do you recall the cost?