My Mini Slingshot

This is my first instructable, so I figured I start out with my mini slingshot. I know its not the first mini slingshot but I believe I have perfected it. I stretched a balloon over a small hallowed out cup and electrical taped it on there. There are many others like it but with those whenever I pull them back if i don't hold them perfectly straight they will hit my hand and it doesn't feel great. http://www.youtube.com/watch?v=zD0S7zrw9WU