A friend of mine used to have one and it was all kinds of fun. It was ,however, a rudimentary design, not very accurate. We once went through a whole bag of 'taters and a can of hair spray trying to ring a church bell. (I'm not worried-- it was a Protestant church. )

Do any of you tinkerers and troublemakers have any design tips? One that could break down and fit into an S2k trunk would be cool...

 

I don't know what design you are using but the one I saw would fit in the trunk.
It was like 3' long.