Bullet blimp.

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Replacing the swivel with a counter rotating barrel gear would allow the rubber band to power both the cone and the propeller. The 3 blade propeller would be connected to a wire that passes through holes in the opposite facing gears and the craft stick frame. The top gear would attach to the propeller and the bottom one to the craft stick and the cone. The loose end of the rubber band would connect to a dowel in the rear.

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This counter rotating assembly has a hollow tube that can house a rubber band! A 3D print job is begging.

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This part is all we need! It can attach at the collars to the propeller and cone cross strut.

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4 plastic miter gears and a PVC cross tee can combine to make a counter rotating gear assembly. Two caps can hold the side gears in place!

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4 miter gears assembly :