Adrian Alexander Mann created a piano with bass strings that are unwound and are at full linear length relative to the pitch they produce.

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Wayne Stuart and his company Stuart and Sons has released a piano called the Beleura which has a range of 108 notes.

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William A. Sethares constructed a prototype of the Hyperpiano, a piano with the string modified to no longer be of consistent thickness, which each string having segments of thicker and thinner wire, which makes the instrument have a vastly different set of harmonics then a standard piano.

Percy Grainger created a 1/6th tone piano to use in his musical compositions.

Doug Blackley- Inventor of the Spectrumpiano.
Percy Grainger- Built a 1/6th tone piano known as the Butterfly Piano
David Klavins- Maker of experimental and expanded function pianos known for the M450 and the Una Corda
Sarah Nicolls- Builder of the Future Piano and the Inside Out Piano, she is interested in expanding the piano.
William A. Sethares- Inventor of the Hyperpiano.
Wayne Stuart- Maker of the Beleura a 108 key piano
Adrian Alexander Mann- Builder of the Alexander Piano, a piano with extended bass strings.
Bjorn Perborg- builder of a functioning sound sculpture that is a 5 key piano