A revolutionary upgrade for the guitar!
With this mechanical memory, you can easily set
your favourite sound on your guitar.
After maxing out the potentiometer,
you can return to the exact same level you were before,
and this value can be changed anytime. Immediately.
It is available in any pot knob design, so it
wont change the appearence of your guitar.
Just replace the potknob and the nut
with the Clutchâ,,¢ Knob and the Clutchâ,,¢ Nut!

https://www.indiegogo.com/projects/clutch-the-sound-marker-music-guitar#/

Is there any other solution you know?