Pen spring powered cannon

This little cannon can be used it in a Physics class, to test different lauching angles and its reach. You can also can annoy your friends trowing little paper balls on them!

To assembly it, print all three parts, take a pen spring and put it around the middle rod. Place all the other parts toghether just as the picture and have fun! There are two holes in the inner rod you can insert something to cock the cannon.

Regular configs for the prints may be ok, I only recommend to print the rod in the horizontal orientation (and supports, obviously), so the layers give more resistance to it.