Good idea, you can get these tanks for $25, and they you are suppose to toss them into the recycling bin. The author just cut it in half and converted it to a fire pit. You could do the same with propane tanks that have “expired” (in NY a tank is good for 7 years then you have to get it inspected to be refilled, its typically cheaper to buy a new tank than to inspect it).
http://www.instructables.com/id/Homemade-Firepit-From-Helium-Tank-No-Welding/?ALLSTEPS