A while ago, John put together a nifty air-powered rocket launching system. It makes for a great party activity for the kids. The rockets are made out of nothing more than construction paper and tape. With some experimentation, he found that bottle caps make good noses for the rockets.
One thing that makes it particularly engaging for the kids is the element of danger. Not so much danger to the kids, but danger to the rockets. If you don't make your rocket rugged enough, the launch turns it into a cloud of confetti.
On a recent trip to Grandma Penguin's house he brought it out. I'm not sure whether the big kids or the little ones were having more fun, but here's a clip to show you what sort of shenanigans we got up to while the kids (little) were making their rockets.
The camera for the rocket is keychain "spy cam" with a micro-SD slot. I just taped it onto the front end of the rocket. Good thing the ground was soft that day. It survived several launches and only really "failed" when I hit a particularly soft patch and the mud squidged right into the hole in front of the lens. I put failed in quotes because the camera continued to work just fine, I just didn't have a good way handy to clean the lens. You've got to love solid state devices. It was surviving some pretty significant G's on landing.
Should you want to try something like this, be aware that there are lots of flavors of this camera with widely varying oneI used. It actually does have the SD card slot (unlike some).