My original thought was to have buttons like a real elevator: a 1st floor up button, 2nd floor up and down buttons, etc. and have it keep track of "calls", finding its way up and down.
I imagined the end product having a remote control that a child could operate with (say) a dollhouse elevator. For ease of implementation, I pared the buttons down to Up and Down. There's no reason there couldn't be more buttons, although if you had multiple calls for the elevator, how long would it wait at each floor before continuing - would you need a "close" door button, or would someone have to press a destination floor button to get the car to move again? It was those kinds of scenarios I decided to avoid, and just have the Up/Down.
If you search for Arduino Elevator, there is a really great elevator control panel someone made - I should follow the instructions and make one and hook it up.
There are so many things I'd like to add - a car with motorized doors that open and close, an interior light, remote control, more configurable floors (number of floors, height, etc.). We'll see if I ever get around to those things. My next goal is to make a hardwired version of the circuit (i.e. soldered components on protoboard). I started on it, but I need to revisit my design. It's different from just plugging wires into a breadboard.
Thanks!
Don