In 2012 I participated in the San Diego CORE project, “Caroushell”. It was a modest sized structure — 20′ round by 20′ tall — but it was complicated, since it had to move, and had many painted elements, and CNC-cut plywood animals, and hanging elements, and LED/EL lighting, and an internal stairway, and was designed to burn (and have the remaining debris collected).
It took us about eight months of Sundays to build it — 32 days or so — with a crew of 4–20 volunteers. We built and assembled it off-site (in San Diego), then disassembled it, loaded it on a truck, drove it to the playa and rebuilt it. It took nearly a week with a crew of 10 or so to finish the build. Call it 350 person-days, give or take.
It was up and working for about a week, with no major injuries and lots of major fun. On Thursday, we burned it, leaving behind great memories and a stronger local community.