I modeled mine after Jim's..
Picked up two shower/tub's off Craigslist free from a remodel..
Then picked up a free hot tub off of Craigslist, it had two pumps in it. I took both pumps and the control box along with the air switches. Hauled the rest to the dump.
Hooked up one pump to each, the tub is the reservoir for the recirculating water, mounted the air switches in the side of the tubs..
Spent a few bucks on plumbing and shower heads, bought expanded aluminum for the floor, made a PVC frame to hold the floor up and wa-la. Low budget awesome working rinse station.
I am not as fortunate as Jim to have floor drains in my shop, so I made a plexiglass door that slides up and down in one of them to stop the water splash out side the tank. I used aluminum channel for the tracks, attached a couple of cables to the top of the plexiglass ran the cables up through a couple of pulleys to a piece of 3" PVC put a cap on the bottom filled with enough sand to counter weight the plexiglass so the door lifts very easy and will stay in whatever position I put it in..