[Okie] designed this audio effect shield for Maple. You’ll remember that Maple is a prototyping system built around an ARM processor, so there’s plenty of power and speed under the hood. First and foremost, the shield provides input and output filters to keep noise out of the system. From there a set of potentiometers let you change the effect, with the manipulation like echo, distortion, and ring modulation happening in the firmware.
You can purchase Maple here.