<-----UPDATED 2/3/12----->

I now have added a locking device in the form of a solenoid. When the amber LED lights up, the solenoid pulls in its plunger from the "lock" (a piece of MDF with a hole in it) and the box opens. I have updated the images to show this change.

So first off I apologize for not making a formal instructable. When I started this project all I wanted to do was jump right in and get it done. If you have any questions regarding the box's construction, coin slot construction, or circuit design, please leave a comment and I'll try to assist you as much as possible. Also keep in mind the construction of the coin slot is not necessary, you can remove it if you don't want to make it. Also I suggest you make the box, drill the holes, stain (not really needed, but its a nice touch), then solder in the electronics. Trust me, it will take longer but its worth it. Speaking of taking a long time, don not rush this project, take your time.

Materials Needed:
- 1 Rotary Switch.
- 16 SPST Toggle Switches.
- 1 Power Switch (also SPDT, but anything works).
- 1 Green LED 1.5vDC preferred.
- 6 VDC Solenoid.
- 1 Resistor 100 ohms +/-5% (Black, Brown, Black, Gold)*
    *The resistor was 15 ohms, but I changed it so now the LED's won't burn out. 
- 1 Amber (yellow) LED 1.5vDC preferred.
- 1 Battery Pack for 4 AA Batteries.
- 1 Box

Misc:
- Plexiglass or other material to make coin slot.
- Stain
- MDF 1/8 for lock latch.

The "codes" are as follows (refer to circuit diagram):

Puzzle Setting 1 (Yellow Line): B1, D2, A3, A4.
Puzzle Setting 2 (Blue Line): A1, B2, D3, D4.
Puzzle Setting 3 (Orange Line): D1, C2, C3, B4.
Puzzle Setting 4 (Green Line): C1, A2, B3, C4.

Once all the correct switches have been flipped, the amber (yellow) LED will turn on.

Thanks for taking the time to read this instructable, all the best in future projects!
- TXTCLA55

http://www.youtube.com/watch?v=Zn3AT1inbVE

http://www.youtube.com/watch?v=trB55p9vwNc