Hello   Here it is from the Horses mouth........   "The way I execute a D roll is as follows: Play the D and keep your finger down as you tap the opposite side (above the keyboard) with one (or two) finger(s) on your right hand. That tap will produce the second D. That same tap will cause the finger you’re holding down on the left hand side to bounce twice if you do it just right. It works sort of like those kinetic sculptures from the 70s that had steel balls hanging next to each other in a