Where can you find a bathtub that has a built-in lift?

Answer 1

Any company that sells or rents medical equipment such as
hospital beds, bathroom equipment and etc. can either order for
you or give you the name of a supplier that makes rehab equipment such as that. I know theres Invacare, and Sam Prestons and numerous other companies that make this equipment or can ship to you. If you still can't find what you are
looking for go to a plumbing equipment retailer and see if they have catalogues for specialty equipment.

Answer 2

A medical supply company