I bought it as an off the shelf from Highgrove bathrooms and then just paid an installer. A lot of installers won't do them because if your walls are not dead straight you can end up with a lot of silicone packing them out which isn't a great look and then people don't want ot pay for the installation. Fortunately these walls were brand new so they were dead straight.
Bathroom shower design fail
Is a curbless shower a good idea?
Before and after of a walk-in shower
Should we put a skylight over our shower?