Found this HOWTO style article on laser engraving dual-sided objects that I thought people would be interested in…
The opening excerpt follows:
Why etch both sides?
As part of my other job at http://marginallyclever.com, I want to make beautiful boxes for my electronics. I want to put a part numbers and helpful maker tips on each piece, for reference… but I don’t want them to show on the outside of the box when it’s done – that would be ugly. I need to etch both the inside and outside of the box parts.
Another great example would be dog tags. On the front I want logos for my club or team logo, and on the back I want something custom for that member.
Flipping parts creates a registration challenge: When the material is flipped it might shift out of place. The first part of the secret is to make a jig that will hold the material in the right place before and after flipping.
The second part of the secret is to make sure the jig has only one line of symmetry. A jig with two lines of symmetry is a mistake waiting to happen – You might flip your parts the wrong way and create a waste of effort.