Made one.. it worked but not well.. we couldnt get the HHO to pressurize and be sucked into the intake nd vac hose.. We did get it to bubble up and it IS FLAMMABLE.. but i guess it has an air leak cuz it didnt do SKWAT for mpg's..
tip Use Stainless wire for the coil.. the galvanized and others rust as soon as current flows thru it.. it starts out as bubbly and clear and soon turns a crusted brown.. Stainless does a good bubble job and does not rust at all..
we used a mason jar and Aquarium plumbing, relays, bolts and alot of plumbers goop to stop the air leaks.., as well as copper wire for power/ground and stainless as coil