Here's a handy little trick I will be trying on a future project! http://hackaday.com/2016/03/28/two-sided-laser-etching/

Lasers
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1

Here’s a handy little trick I will be trying on a future project!

http://hackaday.com/2016/03/28/two-sided-laser-etching/
http://hackaday.com/2016/03/28/two-sided-laser-etching

2

Looks like there ought to be 1 more step (3a), at the flip, you’re going to have to rotate the rear image 90 deg ccw to align it with the front image for the keyed corner to re-engage.