I built a wet-dry vac years ago
I used a 20-gallon grease drum from the truck shop I worked at, a dolly I got from the shop, a new 7 amp, 2-stage Lamb peripheral-bypass motor that I ordered through the shop, an inverted plastic hanging flower pot for the motor cover, and the hose, hose port, and tools from my orange Eureka 550 canister. I used a Shop Vac pleated filter held in place by a threaded rod and wing nut. It didn't have a float or float cage, but I tried to be careful not to let it overfill. It did once when I drained my parents' washing machine, but I shut it off immediately and the motor soldiered on unharmed. When later I got a real shop vac, I re-assembled the Eureka along with an orphan Eureka power nozzle I bought at K-Mart for 8 bucks, and used it for several more years until our volume of cat fur led me to purchase a full-sized Eureka upright.
I never took pictures because I built it for function, not looks. It certainly wasn't a thing of beauty, but it advertised nicely for the oil company whose product it once contained.
As an aside, that motor found a second home in the organ pipe blower of our custom-built player piano/nickelodeon.
As a second aside, shortly after I built the vac, a water pipe froze and burst above my parents' living room. I came home early from work and pulled up the water, saving their carpet. Their insurance company paid me for the cleanup because I spared them from carpet replacement.