It looks like that thing is basically a pulse-jet, the same engine used in the V-2 "buzz-bombs" (c. WWII). Cheap to build, just a combustion chamber and nozzle. Looks like Andy used old plumbing parts. Nice touch using the fuel tank as a bumper, Andy.
Just think about it, in all seriousness: Your friends come over for dinner, and look down at the dining chairs, table, couch, lap, etc., all equipped with a properly sized pulse jet. When the obvious question comes up ("Uh, what in hell are all these things attached to your stuff"?), you can reply, "They're jet engines. I don't f__ around anymore, Frank. Don't touch. What can I get you to drink?"
Yup... this guy is gonna be a crispy critter. It'll be spectacular, I'm sure - sort of real-life version of the "JATO-powered Impala"