Here's my 100% scratch built jet pack. The pictures are way shinier than reality but at least the color comes out about right.
The rocket consists of some pipe couplers, 2 air fresheners and a cut down funnel. The top is like a hollow point so I'll call this one Fett's HESH rocket. (High Explosive Squash Head) The main body is sintra while the main tube is ABS pipe. (3 1/2") I'm guessing the weight about 4 lbs +/-. The fuel tanks are small paint cans but they'll be upgraded. The thrusters are air fresheners epoxyed to 2 plastic balls. I drilled holes in the large dowel and put in a 1/4" dowel on each end. The balls just slide on and they are pretty secure.
She's not movie accurate (the tank enclosures are 3 sides instead of 4) and she still needs the greeblies but she's all mine baby! I'll try to make my templates available soon.