Hamm Brushland’s AutoBong has been floating around online for a few years now. The rig uses a pump and gravity to automatically pull a cone and push the smoke out of hole at the top (that can be connected to a hose and passed around… or just smoked).
Now some stoner has filmed a video explaining where the pressure is and how the fuck it actually works. Interesting stuff – though it does seem to take the fun out of smoking. Perhaps helpful for those with emphysema. There’s also a vid of the bong working with smoke, too.