I had/have the ruffler for my vintage machines. I could never figure out how to measure to make sure I had enough fabric. It would have helped back in the days when I was making the ruffled curtains, and clothes for my DD. I spent way too much time pulling threads.
I do have to check for the elastic foot on my Brother too. That may be useful

I will have to check on one of these feet for my machine :D:D:D