One of the fundraisers that my troop has done was a car bash at the city fair. We asked a local salvage yard to donate a car (and they did)and we set up a little booth and charged people a buck a hit or five bucks for like 10 hits. If the person hitting knocked a hole in the car or knocked a piece of the car off, they got a free hit and they got to keep the piece if the wanted. Of course, we got an old school American car, so it was kinda hard to put a hole in it, even harder to knock a piece off.
And of course saftey would be an issue, so we had to knock out all the glass before anybody could hit it, rope off the area, use saftey goggles and only allow one person at a time to hit the car. But we did get pretty nice amount of money. (for anybody planning on using this idea, bring more than 1 sledge hammer, for they will get broken)