I think the real innovation here is using an inflatable form. This could be cool with a spray on concrete too, like Gancrete: http://www.grancrete.net/videos/i

I think the real innovation here is using an inflatable form. This could be cool with a spray on concrete too, like Gancrete: http://www.grancrete.net/videos/index.cfm# http://www.grancrete.net/videos/index.cfm#