This brings back memories. – Überdoodle Review

I remember playing with Spirograph in the 70s. This app is a great alternative and a lot of fun. Plus with the ability to create your own wheel and ring sizes (number of teeth), it's interesting to see geometery in action - put a number 60 wheel in a 120 ring and you get a single loop no matter which hole you put the pen in. You can also shrink and stretch the rings - something you definitely can't do with the real thing - so you can make patterns in all sorts of sizes. They have a limited free version, but it was well worth the $1.99 I paid to get the full version. The only thing missing is a ruler shape with teeth on the outside, but it's still fun to play with just the regular rings.
Review by vgehts on Überdoodle.