The original design is by Matthias Wandle which he wrote about on his woodworking site, woodgears.ca. The design uses a captive bolt, powered by an elastic band to blast the Jenga block out of its space before it knows what's hit it! I visit his site weekly so had read about his attempts at selling some of his Jenga pistols, which didn't go as well as he'd hoped because the interest had died down and they took too long to make in wood.
His efforts inspired me to make an acrylic one which I could laser cut, not to sell, but because I have a laser cutter and it was faster for me to do it this way than with wood, plus I've always wanted one after I saw his.
This Instructable shows how I designed my version and how it works, as well as some of the other fun I've had with it.
Step 1: Design
Before laser cutting my prototype I drew it in the CAD package I use, Alibre Design. This let me throw together a full assembly to check all of the pieces would fit, then export them as a DXF for the laser cutter.
My design was based loosely on the one by Matthias Wandle, I changed the way I attached the rubber bands to suit laser cutting better and changed the stock. Since it didn't add any machine time I later added some flourishes to make it look fancier, like a pretend sight and some grips on the front of the stock.