Caesar Cipher Wheel

Caesar cipher wheel can be used for teaching cryptography or for a game with children. It's actual size is the size of CD/DVD (120 mm in diameter). The inner wheel is 90 mm in diameter and there are two types: + with alphabet clockwise and - with alphabet counterclockwise.
The cipher can be negotiated in advance and may not be part of the message itself, or can be at the beginning or at the end of the message.

3D+R W1.AV6L

This cipher is on the photo of the prototype.