I was involved in several, starting when I was about 10 or 11 with jobs like sweeping up sawdust or picking up loose nails. I loved it. Once, when I was about 22 we were building the KH south of Santa Barbara in Carpinteria. We were doing the hot tar roof and some volunteer helper sloshed a bucket of scalding tar off the edge of the roof and it splashed on a brother down below. Got his right arm and hand. He was taken to hospital with a very bad burn. Of course, the Society got the real property and he got the medical bills.
Seemed their were always brothers in the construction trades to supervise and I remember them all as great guys. All in all, building Halls and working in food service at the conventions was the most fun I had with Org. related activity.