Okay, this looks TOTALLY crazy to me. The DIY movement I usually admire – the why-buy-when-I-can-make-it-myself crowd. But carbonation is SERIOUS business – you’re dealing with pressure and things explode. Seltzer delivery men had to (and still have to) contend with the potential of losing hands to exploding glass. Yet, some folks would rather take the risk.

For those looking for the “Clffs Notes” summary of how this works: Take a 20lb CO2 Tank and regulator, attach a tube, and stick a 99 cent locking ball air chuck (tire inflator) on the end of the tube. Pop a cheap snap-in tire valve (schrader valve) into a plastic soda bottle cap and you’re ready to carbonate any liquid in about 30 seconds. Colder liquids absorb more carbonation.
And in the end it still costs $100. Why not just by a SodaStream? Of most interest to me are the health and environmental reasons justifying this towards the end.
More at Instructables.