I made my own washer 20-years ago from acrylic - I copied as well as I could the Zone VI washers. It worked for about 15 years and then began to leak.

I've now bought a 10-gallon aquarium, cut a couple of pieces of PVC pipe the narrow width of the tank, and cut slots in the pipe for dividers. I put the pipe in the bottom of the tank then slip the dividers into slots. I use a siphon to fill and drain the tank. 8x10 is my largest size, so this arrangement works well for me.

With the development of akaline fixers, I don't believe there is the need for the extended washing that there once was.
juan