The Singer Featherweight (introduced in 1933) was revolutionary in that it was made to be portable. Unlike the earlier cast iron models, they were cast of aluminum. They haven't been made for decades now, but are still very popular, especially with quilters who often travel to meetings or shows and want to take a machine with them. As it happens I listened to this interview last week and could find it in my YouTube history: Why the Featherweight Became a Sewing Legend. I've advanced through the video to almost 6 minutes where he starts talking about the history. This guy restores the Featherweights and you'll learn a lot if you listen to the whole thing. (Raises hand - I learned how to sew on my mother's Singer Featherweight.)