My mate Joshua Herbst recently shared this video with me of the first ever “fluid” piano invented by Geoff Smith.
The completely acoustic piano allows the musician to tune every string by a whole tone either during the performance or before hand in order to set up particular microtonal scales.
The fluid piano sounds beautiful, reminiscent of sitar, but with a deeper tone quality. I can’t wait to hear more from this ingenious instrument.
Here’s the original article from the Guardian:
Introducing the ‘fluid piano’
This as yet untitled rough mix is made up of a few simple melodies recorded on my 1916 Raudenbush & Sons upright piano. Interspersed within the piece are a number of what I’m calling piano sound objects. I used a couple of different techniques to create these sounds. 
I recorded these gentle piano chords on March 25, 2008 while working on a classically influenced piece of music. While re-listening to this today I had the idea of damaging the recording as much as possible with processing to see what I might end up with. The main reason I decided to do this was because I was dissatisfied with the sound of the original recording and thought, perhaps I could get something interesting by degrading the signal significantly. I tried a few different types of processing but settled with heavy limiting followed by a high shelf into monster distortion, topped off with almost 5 seconds of reverb. 
Here’s another example of using a mallet to get sounds out of my piano. In this case, instead of striking the main part of the string, I let the mallet bounce on the small piece of string after the bridge. This part of the piano is traditionally not used to create sound and the pitches are quite high and not tuned, similar to the area between the tuning pegs and the nut of a guitar. 
This dissonant phrase of piano was created by using a metal mallet to gently taps the stings on the piano in the upper register. I’ve been experimenting with getting some unique sounds out of my piano by not using the keyboard.