I've done a double fold piano key binding using 1" (finished) keys and it was extremely bulky. The corners were impossible to miter neatly, the hand stitching on the back was very difficult to keep hidden, and it was just a poor finish. My advice for any mega-pieced binding would be to make it single fold only because of all the seam allowances inside.
Last edited by ghostrider; 01-18-2014 at 07:38 AM.