My third angry bird order... and I still think they're pretty darn cute:
I made the slingshot by taking thick wire and bending it into a U shape then shoving it into a giant straw (bubble tea straw). I then molded the fondant/gum paste around it.
That wood grain impression mat has come in SO handy. I use it all the time. You can find it here.
Don't you think my birds are getting better? I think they look especially angry.
Here's my original Angry Bird Cake: