How I built mine:
Plumbing - extended 1/2" hot & cold water lines through wall, elbowed up, 2 valves, then a tee to a single shower head.
Floor - shower was built in a corner of a patio. lifted a 6'x6' section of pavers, regraded the stone dust to a center low point; installed a small yard drain which I piped(4" drainage pipe) to the closest gutter drain; re-layed the pavers whic now pitch to the drain. Then I built mahogany wood floor. Walls are 6' vinyl privacy fence on 3 sides(4th side is house) with door.