I decided to build a helicopter out of knex. It does not fly but the main rotor and the tail rotor both turn at a pretty decent speed. I used a knex motor but it was too slow so I just soldered on some wires so I could power it with a 9 volt battery.
I'm not too sure how to explain how I did it so I will just post pictures of various steps. There is also a video at the end
Step 2: Completion
I hope my pictures are easy to follow. It's a fun project to do. You also may need to make some adjusts so that the gears mesh properly. Thank you for the views :)
Here is the link for the video: http://youtu.be/0dQEX_gPg00