1990s vintage - we had fun making spiral drawings in various colors and experimenting with how the different gears work, and maybe someone else can have fun too. Sadly a few of the gears are missing, and of course the pens are long gone. I'm including the pen I used to make these recent examples, so you can easily see how it works.
From a dog-friendly home.
Twirl O Graph design maker toy (North Juanita area of Kirkland)
This offer has been gifted to someone and is no longer available.