We did three projects for this program. The first was craft stick catapult. You can find instructions how to do them most anywhere. For ours, we used 9 crafts sticks, rubber bands, and a plastic spoon. Of course, once we made them, we had to test them out with pom poms. We used them two different ways: using them on the floor like the picture below and holding them in our hands and using them. I think we could have done this for the entire program honestly.
I found a great construction paper bridge craft on ehow. My phone died, so I was only able to take a picture of the sample I made. Most kids did their own thing and created smaller bridges or rafts. It was really cool.
Lastly, we have cardboard blocks, so I challenged the kids to make various size towers with them and see how high they could make them without it falling down.