For the same class where I started off by making an edge-lit sign, my team built a deck shuffler. It uses an Arduino to control a small motor on each side of the frame which spins a cylinder to spit out cards. The 3D-printed cylinder is wrapped with heat-shrunk plastic to give it a better grip on the cards.
While our presented version was hastily built, I think some minor modifications would improve it quite a bit. One would be changing the Arduino code to lower the maximum time that each side can run, so the machine evenly shuffles. Another change would be adding sensors (likely photodiodes) to make sure the card clears the slot as well as counting how many cards have gone through per spin cycle.