I think scrappy is just that scaps! No fat quarters or large pieces. Throw the scaps in a container, reach in and grab one. It's suppose to be anything and everything. No color combination. Just whatever you grab is what you use.
It would be neat for everyone to bring a plastic tote or box full of scaps. Set the machines up, then keep passing the containers around and just reach in pick up a fabric and sew it on. That's scrappy to me.