It's also my understanding that if you bought a partially completed kit,
built by another amateur, you can still be the "builder", even if you only did a
small percentage of the work. But only one builder can be listed on the
form, and only one person can get the repairman certificate. So multiple
builders can be involved, either sequentially or concurrently, as long as the
sum of their work is 51%.
There was an ES at the Rocky Mountain Fly-In a couple years ago built by a
high school shop class over a number of years. It has a plaque listing all
the names of the builders who participated, about a hundred. I bet the FAA
paperwork had the name of the shop teacher, or the donor of the kit.
John, I'm still curious about the exact listing on my FAA paperwork.
Mike