Just in case you've missed my reference to my new favorite website, click here. In any case, they recently pointed to a laser guided slingshot, complete with videos that show that even a girl can work it.
The interesting thing is that the concept isn't that difficult. The unit depends on a pivot between the handle and the fork which floats in the tension of the bands. A second joint at the top of the fork tracks the up/down angle of the pouch. It also depends on balancing the elastic (if one is stretchier, then the laser won't track) and the trajectory being flat (it doesn't allow for distance drop).
Now I ask, how hard could it be to make one of these in the basement?
To ease your minds, I am not considering anything like explosive shot, infrared lasers and night-vision goggles to see the infrared spots with. That would be nefarious.