It's EXTREMELY clever-- the way you arranged the black keys in twos and threes. I really had to zoom in in order to figure out what parts you used for that. As a music teacher, I thank you for your attention to detail!
Quoting Raviel Ze MOCist!
Matija,I'll be honest.Did you use a design like it or similar for the Piano?Well...because I thought I saw something like it.
There are lots of LEGO piano's on the web, but I haven't looked at any before building this one. It is a small model, and I suppose there is lots of similarity between all models - it's to be expected. But if I used someone else's design I would told so. So, no. :)
I tried to make an electric double-platformed keyboard for minifigure and it doesn't come close to this. Great thinking outside of the box with the sideways-orientated bricks making up the body. Awesome detail and display!