Since I don't have time to retroactively log what I've done, here's where I'm at.

I currently have a rugged waterproof case, a promotional video brochure that has been disassembled, and Arduino mega, and a bunch of switches, LEDs, and components, along with a couple different potentiometers, some mini OLED displays, and a plethora of other things that I probably shouldn't try to include. 

I have cut a piece of thin veneer plywood to fit the bottom of the case. I plan to Mount all of the switches to this.

Goal:

My goal is to place a decent number of switches on the board, along with enough LEDs to depict each switch position. I'm laying them out so that I can create a puzzle at a later date that requires switches to be turned on in a sequence and the LEDs to visually guide that sequence.  

I'm leaving room for the OLED displays but will likely not have time to incorporate them right now.

The promo video card will be completely separate for the moment,  and will activate using the hardware that came with it, including the magnet to turn it on when the case is opened. I will replace the three buttons with my own buttons that will be a little more rugged.

Challenge:

The main challenge I see now is power. I think I can design it to run AAAs but it would be nice if I could incorporate a set of 18650s and a charge circuit. The other challenge is determining how to mount the Arduino and all of the wiring to handle the rugged environment of a 2-year-old!