We went to the Rijksmuseum in Amsterdam and after looking at the fabulous Rembrandts, I went up to the third floor where the modernist stuff is. A 1931 film by Joris Ivans showing the Philips Radio assembly plant was on a loop, and it got me. I've been hunting for it since we got home, and finally found it. It shows all aspects of the radio assembly process. The speaker building is very cool, especially the use of an hourglass to time the cone press. It's about a half hour film, and the speaker part is near the end, but it's a striking film worth a watch. This was the best place to put it I think.