How to cast a chair in one piece…
I wondered and made a mold, placed the mold into my self made vacuum tank, drew out the air and replaced the vacuum with a liquid polyurethane rubber. After setting the mold was opened and the rubber chair came out exactly as on the photo. This all sounds real easy, obviously it was not. A modest metal frame is suspended in the mold providing extra support for legs and back, all else is rubber. The chair looks ridged but is remarkably comfortable.