Devices capable of gestural interaction through motion sensing are increasingly becoming available to consumers; however, motion gesture control has yet to appear outside of game consoles. Interaction designers are frequently not expert in pattern recognition, which may be one reason for this lack of availability. Another issue is how to effectively test gestures to ensure that they are not unintentionally activated by a user’s normal movements during everyday usage. We present MAGIC, a gesture design tool that addresses both of these issues, and detail the results of an evaluation. ACM Classification Keywords H.5.2: User interfaces—input devices and strategies; prototyping; user-centered design. D.2.2: Design tools and techniques—User interfaces General Terms Human Factors