Does / Could a lock like this exist?

[mechanical_nightmare]

The earplug material is a brilliant idea. It should take less time than the dental floss method too. Has anyone tried using earplug foam or other similar material on pin tumblers instead of using a plug spinner? It sounds like it would be especially useful for dimple locks where it is comparatively easy to insert material into the keyway. This also gives me some ideas for auto-impressioning techniques.

[smokingman]

I don't think it would work for impressioning.
It will not make a copy of the whole key, just help the wafers stay in place while you quickly turn the plug, not giving enough time to change shape as the wafer profile would when going from open to locked and back again as it gets unscrewed.
It can't be left in for too long, and if the cylinder is in the locked position for too long
it will push the wafers into that profile and you will lose the unlocked profile.
You get expansion as soon as you pull the material out unless it is very cold,
and takes more material when cold and it gets deformed anyway from being pulled out.
It's not magic ,or lock goo, but works better than some other things did for me.
I any case I would not use this method until you are thouroughly familiar
with the time and temperature limits of this material and only experiment on your own locks.

[mechanical_nightmare]

I see. It was just an idea. What you are describing seems to work as a kind of plug spinner. In that way it is similar to the method where you pack the cylinder full of dental floss after you pick it, and then (quickly) rotate the plug past the pins again. And yes, I would not experiment on any lock that is mounted, even if it is mine.