Plastic bubble bottles-you remeber when you were a kid and you got the little bottle of bubbles (basically dish soap and water) with the wand in it. Well Walmart had these giant sized bottles for 88 cents. They're almost 3" across. They top has a very similar shape to the tops of the tanks on the jet pack. The bottle is too short though, so I just cut it in half. Tell me how and I'll post a picture.
When you're looking for parts just use your imagination. I put pictures in my pocket and wander around Lowes, Home Depot, or where ever and try to find things that will work. Depending on where you live you might find something that works better than something else. I don't think it really matters what you use as long as the end result looks like a jet pack. Be creative.
