-a disposable cup
-some soft threads
-a coil of wire
-Arduino Uno board
-motoproto shield with Arduino
-a motor: EXI S1123 9G Micro Servo
Make a jellyfish body with a disposable cup.
Use threads to attach the motor to the jellyfish body, with the motor plugged into the A2 port of the Arduino Uno board.
Connect some LED in a parallel. Attach them to a round paperboard, which is about the size of the jellyfish body. Connect the LED anodes to the positive terminal of the wire (wire B) extended from A3 port of the Arduino Uno board. Also, extend another wire (wire A) from the cathodes of the led.
Use electrical wire to make a small fish, and connect it to the negative terminal of wire B with a conductive thread. (The fish should be conductive.) So that once the fish touches wire A, the circuit is completed, LEDs will be lighted up.
Attach the round board (with LED) to the jellyfish body. Keep one end of wire A out of the jellyfish body, so that we can “feed” Jelly with the small fish from outside to light up the LED. Here I decide to cover the jellyfish body with scotch tape to hide its internal organs.
Plugged the Arduino in to your computer, and set up programming with Modkit (http://www.modk.it/), so the jellyfish could move as you want it to.
Decorate the button of Arduino board. Make it look like a son jellyfish.