In this Instructable, I'll tell you about how I laser etch designs onto chocolate, and the tips and tricks I have found so far.
The most important insight when working with chocolate is that the etching works more by melting and re-settling the top layer of the chocolate than by vaporizing it. This means that the etching is a fundamentally unsubtle process, and also has implications for the resulting colors, the resulting structures, and for handling the chocolate in the middle stages of the process.
Step 1: Pick and prepare a picture
For the design, don't try to be subtle. Grey shades don't carry particularly well: the most clearly articulated part of etched chocolate is the difference between etched and not etched: different shades will be hard to pick out, if at all possible, in the finished product.
For our running example today, I picked a picture of the Golden Gate Bridge I took a while back. The picture is already in black and white, so we can skip the greyscale conversion: however, I would recommend you do convert your image to greyscale — this gives you more control over what parts of the image are dark or light. However, to emphasize the shape, I used Photoshop's «Posterize» filter to get a more quantized image with very few grey scale steps.