I have seen some very sophisticated egg decorating machines, but all of them needed precise positioning components, so they are not especially easy to build. Further more your creativity is not involved in the painting any more.
With my solution you still have the possibility to add your personality to the decoration, and it is also very easy to build.
It is basically a lathe, where the rotation is controlled by an exact motor. You hold the pen in your hand, that is the tool for the lathe. You can choose from different rotation patters while you control the pen movement by yourself to preserve the creativity.”