The simple part of the hack is using an adapter to connect the Sodastream apparatus to a 50 lb CO2 tank from the welding store. This is easy enough, and just uses a off the shelf adapter.

All you need is a local supplier of food-grade CO2 in cylinders, and you can visit them when you need a refill or swap. There are several caveats, though, which the comment section dicussed when ...