You are correct, I had forgotten about the last experiment with the light shining across a distance. For some reason I thought that the gyroscope was the one that they ended on.
Bob may have been confused about the shape of the Earth, but he was still a person with family and friends. A good thing to remember about all of these people.
So a manual mill and a receiver blank are not? If you wanted to build something like this yourself, this is a better option than a 3d printer.