For our project, we created a shadow puppet show.  We did this using multiple parts behind a screen to tell a story.  The story is that when the audience rings the doorbell, it wakes up the skeleton.  The skeleton taps the spider on the shoulder.  The spider then goes down to the basement to get the candy basket, which it then drives out to give audience members candy.
 
When the doorbell (a touch sensor) is rung, the skeleton rises from the grave using a large motor.  It stops rising when the lower part of its backbone hits a touch sensor.  When this touch sensor is pressed, it causes the arm to tap the spider on the shoulder using a medium motor attached to the lower-neck of the skeleton.  After that, the spider descends on a string attached to a large motor above the screen to go down to the “basement”.  In the basement is a cart with a candy basket that has an EV3 daisy-chained to the main one used to control the spider and skeleton.  The second EV3 is attached to a cart that carries the candy basket out.  This cart has two large motors attached to the back wheels.  The spider then “drives” the cart out, allowing people to get their candy.  After a few seconds, the spider brings the candy cart back, goes back to his pearch using the same large motor as before, and the skeleton goes back down to his grave.  The robot on top of the trap door has a conveyor belt that covers it with the fabric.
 
We programmed the robot by daisy chaining 2 EV3s and opening the schematic diagrams in Labview.  We then renamed the ports that each of the motors were plugged into as skeleton rise, spider, car 1, and car 2.  We also had the sensor ports renamed start program and skeleton.  First, the program waits for the “doorbell” to be pressed.  Then the skeleton rises by turning on the “skeleton rise” motor and the program goes into a for loop that moves the skeleton's arm twice.  Then the “spider” motor moves the suspended spider to lower into the basement area.  “Car 1” and “Car 2” then turn on, allowing the car to come out and wait for people to get their candy.  The program then runs “Car 1” and “Car 2”, "spider", and "skeleton rise backwards to reset the program.  The whole program is in a while loop with its condition permanently set to false so it runs infinitely.
 
One challenge we faced was stabilizing the “skeleton rise” motor so that it could take the weight of the skeleton and the medium motor attached to it.  We did this by attaching legs to the bottom of the motor to be able to support the structures.  Another challenge we faced was finding a way for the skeleton to rise up to a 90 degree angle every time.  Originally, we just had it go up for a certain number of seconds, but then the calibration would get messed up and the skeleton would rise to a lower and lower height each time.  We solved this by placing a touch sensor at the base of the skeleton’s backbone so that the “skeleton rise” motor would stop when the skeleton hit the sensor. Lastly, we faced the challenge of placing large, bulky the candy basket on top of the cart in a stable way.  We accomplished this by poking holes in the bottom of the basket and putting Lego pieces through it as a structure inside.