Piano tuning key tool

[rendoman]

Hi!
For piano enthusiasts that's a tuning key. I bought from Aliexp the socket (common size is 2, for Petrof also 1 could work). The original thread was a 10x1mm, not very common here, I decided to machine and tap the standard M12. I decided to use a 316 round bar, pretty long to have control.
With a bit of rubber stopper and a good app is possibile to keep the piano in tune at home.