Click button and then draw something with mouse (mouse down to draw). (Limited time available - only until the "trackers" reach their end points.) For best results, draw smoothly, not too fast, and start and finish in roughly same place. Computer then "builds" a machine to try to replicate what you drew. See notes for what is going on in this.
Plenty of Fourier projects on Scratch but he is in the big pile marked "important stuff I wish I'd learned when I was younger" so wanted to do one myself. Joe F's amazing and useful discovery was that waves, signals etc can be broken down into simple components - here just circles rotating at different speeds, stuck together. Fourier analysis seems to be a pretty key concept in all sorts of scientific fields. Loosely inspired by @Jie's great projects (hamster drawer and Fast Fourier Transform - the latter being a much more sophisticated tool based on Fourier). This uses two "machines" - for horizontal and vertical movement respectively. Didn't know how to combine into one.
