This idea originated in 2010 with a junk propane tank on my property that my wife told me to get rid of or "do someting with." A lot of energy had been used to form the thick steel into this shape and it seemed a shame to let it go to waste. I considered possible ways to carefully dissect the tank and reassemble the pieces into a seat as we needed a place to sit in our garden. I was intrigued by the design challenge and ecological statement involved in taking this ubiquitous, utilitarian container out of the waste stream and transforming it into an object more sensuous in form and sophisticated in function.

After making sure the tank was purged of any remaining gas I began by cutting off the hemispherical ends and mounting them on my work table.  

Next I welded in a seat from the  cylindrical portion. Although I had never done this before, and was unsure my plan would work, I had a friend take an amateur video of the  process just in case (below).  I also posted on  Instructables.

With the first bench a success I looked at the remaining tank material (pictured on left) and realized I could make another bench.

There was still left over tank material so I kept going and made a third seat.

By the time I was done I had reused almost the entire tank.  These scraps were all that remained.

Inspired by this process I located more salvage tanks and began to create additional designs.

After lots of testing with friends who ranged in height I determined a universally comfortable relative position of seat to backrest. The combination of curved seat and curved backrest provides good lumbar support for a wide range of body sizes as small bodies are able to slip slightly further back and down into the seat.

genesis

And a fourth.