Our co-op was planning a trip to the Renaissance festival and to get the kids excited they made shields. These were pizza signs, nice and sturdy, the kids painted. They spent a ton of time on these, some probably three hours.
They also made catapults. No directions were given and they came up with some very successful designs.
Shooting them off, they all worked!
All the shields, these were great. The little girl in the white dress - the kids made that out of tissue paper. It is amazing what they can do when left with craft materials and unlimited time.