My previous code wheels printed in 3 parts, which takes to long and limits the number of simultaneous makes. So I started from scratch, and made a new design that prints faster and in one piece. It's also a bit prettier, I think. I've included the Fusion 360 file, so you can alter your alphabet. 

I've also created a v3 model, which has a tighter tolerance. Depending on your printer, the v2 may fall apart pretty easily. 

This does not print well with a brim. Also, the 2 pieces may stick a bit at first depending on the first layer height. Once they work free, the wheel spins well. 

I also created a little python program to generate Caesar ciphers from a text file. It's handy if you want to give these to a class as a project. Check it out at https://github.com/Thomsedtech/caesar_cipher . There's a sample of the output, with encoded song lyrics and keys, also. So if you want to entertain some kiddos, you've got everything you need!