David Glicksman of LA, California, wrote in to share his Secret knock-detecting workshop door:

This is (what I think is) a great example of the kind of fun, inspiring projects that come out of communities like Make, BoingBoing, and the DIY nerd world in general. I combined Chris Schaie’s beautiful Mechanical Iris, Steve Hoefer’s Secret Knock detecting Arduino code, and an engraving made with my scratch-built CNC-Router to make the entrance to my garage/lab a bit more special. These people all inspire the hell out of me, and I just want to feed a little bit of that back to the source.

(Hopefully he changes the shave-and-a-haircut combo to keep his workshop secure!)