First tests with a vibrating motor:

• needs some more unbalanced mass that the vibration is more powerful
• little case for the motor that the strings getting not entangeled

Second tests with costume:

• the costume could have a seperate cape
• the cape has maybe 2 “layers” – one for the strings and one for the motors
• so the motors cannot get entrangeled with the strings (and can be as big as it needs)
• the motors will vibrate the whole surface