If you’ve ever celebrated the Easter holiday, then you’ve probably decorated some eggs. People have actually been decorating eggs for far longer than Christianity has even existed. Some decorated ostrich eggs have been found in Africa that are 60,000 years old — predating recorded history by many thousands of years. Eggs are typically decorated with various dyes or paint, likely because they show up nicely on those pale white shells. But modern technology has given many more ways to decorate our eggs. If you have a CNC machine of some sort, you can follow Leogala's tutorial to laser etch grayscale photos onto your eggs.
Engraving an egg requires a CNC machine with at least three axes, and one of those axes has to be rotary. In most cases, the easiest thing to do is add a fourth rotary axis to a typical three axis CNC machine. This guide covers how to do everything with a DIY RootCNC machine, but just about any machine that can be expanded to include a rotary axis and that accepts G-code should work. The rotary axis is important, because it spins the egg so that the laser can reach the entire surface of the egg shell while remaining in focus. Leogala explains how to construct that rotary fourth axis, but connecting it will depend on your specific machine.
The laser module used by Leogala is 5.5 watts and operates in the 445 nm spectrum. That module itself costs around $55, but you will need a few additional components to utilize it. For example, Leogala used an Arduino board to build a temperature monitor that will pause everything if the laser tube gets too hot. After you’ve calibrated your machine, you can then create your G-code. To do that, you first need to use a depth sensor to generate a height map of the surface of your egg. That tells the software what position to move the Z axis to as it engraves. Finally, you can use the free LaserGRBL software to convert an image into a G-code file. Then simply coat your egg in a consistent layer of paint, wait for it to dry, and etch. Sure, we still have several months until Easter, but it’s never too early to start modifying your CNC machine!