Some weeks ago i found chris schaie's [1] iris on hackaday [2] and i was so amazed that i took a screenshot from the video and made my own iris based upon his design.
From there it was a long road but eventually my own design worked out and i managed to create a mechanical iris that can be opened with a stepper motor.
Now we have a welcoming system at the metalab [3]

[1] schaie.com
[2] hackaday.com
[3] metalab.at

This is a pretty generic key fob that can be cut out from Acrylic on a laser cutter, modeled after plastic ones ubiquitous in Austria. It comes with a bit of space in which you can engrave or cut the text/symbols you want.

It's 1.5 cm x 5 cm, which should be enough for two lines of readable text, or 2-3 nice and large symbols.