Here's how we modified the
Jerry Cans to be used as foam generators.
First I visited a local hobby shop and picked up 2 packs of Du-Bro fuel can cap fittings. Next I drilled a hole within an inch from the original spout. This hole placement is somewhat important because you need to be able to reach it to insert the threaded fuel line coupler once the hole has been drilled. Use a bit of RTV silicone sealant around the hole to seal against an air leak before you snug the brass jam nut down.
Next I visited WalMart and picked up two 9 inch aquarium air-stones. I connected an air stone to a piece of tubing (also picked up at WalMart) I used a few ties to fasten a couple of stainless steel bolts to the air-stone to keep it weighted to the bottom of the Jerry Can. The tricky part was to use a hemostat through the original opening of the Jerry Can to place the tubing over the bottom side of the fuel line coupler.
Then it was a simple matter of dropping the air-stone into the Jerry Can. Add tubing of sufficient size to go on the original spout of the Jerry Can which will be routed to the end of the boom for the foam drop.
The Jerry Can is filled with water, the soap solution is added, ( I used an ounce of concentrate per 5 gallons of water in my tests). When 2 psi of air pressure is added to the aquarium line the foam is produced in large quantities. Play with the air pressure for varying results and consistencies of foam.
NOTE: Since I'm going with two Jerry Cans, one for each side of the boom which is why I purchased 2 of everything. You may want to just use a Y connector and split the foam from one generator to both sides of the boom. I don't know how this would work since I haven't tried it myself. If you do decide to try it I might suggest keeping both lengths of tube to each boom tip the same length so one side doesn't get more foam than the other side.