For my 6 grade design class, I made a shooting cardboard arcade. Players try to shoot a ping pong ball from the shooter we made and try to get the ball in any of those hoops (The shooter can move to any direction).
One thing I learned from the arcade project is not wasting things and still making better projects. For example, when we used hot glue, we covered the whole line and then sticked it. But instead, we could just glue the corners and stick them which uses much less glue and is very stable.
If I did this again, one thing I would do differently is making the shooting thing a little closer and let the ball fly a little lower because in the arcade, a lot of fourth graders thought that it was too hard because they always missed it short and high.