The computer setup is a normal raspberry pi 3, with an adafruit servo controller hat. There is some adjustment needed depending on the length of your pusher arm - this is in the python code that controls the servos. It is really nice to be able to see the stack of coins, and how many are left in the tube. I originally used a black PVC tube, but I found a cheap clear alternative at TAP plastics.
The stack lives inside a plastic tube or pipe. In our mechanism, we separate the stack from the dispenser. It has a piece of plastic the height of one coin, and it pushes the coin from the bottom of a large stack. The design was borrowed from a change dispenser that I have in my old coke machine. I had some success printing them using these: servo arm CAD Ultimately we used the servo arm that came with the servos, and overlaid a laser cut piece of wood. I created the models using openscad: Chocolate Coin CAD files The servo horn needs to be longer than the standard horns that come with the servos. I used this as an excuse to purchase a Taz Lulbot 3D printer. The first prototype was built from cardboard and scrap wood. The first part of the project was figuring out how to reliably dispense chocolate coins.
