Pumpkin-pult!
I have only made the catapult with popsicles and rubber bands. In my experience, older elementary students had no trouble making this. Younger learners had trouble wrapping the rubber bands around the popsicle stick. These catapults are a great introduction into how engineering can be used to solve problems. Setting multiple distance and accuracy challenge make this activity a ton of fun.
Next time I try this with my science club, I will try using different materials to see how creative our catapults can get. This would be the perfect project for if your school or home has a makerspace.