Hi,
There is a thread on DYI washers in this forum. Search for Archival Print Washer Kit. In the thread, Jeremy Moore posted this link to a vendor: http://fineartphotosupply.com/printwasherpage.htm. It provides the "insides", you provide a 10g aquarium tank.

Looks pretty easy to do, even without the kit.

Cheers,
Geary