I had a brilliant idea once, but I never actually tried it
What you do is you get a BIG and I mean BIG steel tool box. Build a rack for it to mount on, build a friction setup, preferably using a clutch. cut some holes in the right spots on your tool box, and then get this incredibly quiet and reliable 2 stroke, 1.2hp japanese engine Goped Engine G23LH G23 LH : Engine Motor Engines Motors Goped Go Ped
and mound it sideways in the tool box so the exhaust goes out the bottom and air comes in on the top. All you need is to cut a few discreet slots for the hot air to pass through and you're set
I'm gonna do it someday!