Who left the garage open?

My kids love my keys and all the gadgets attached to them... including the remote garage door opener attached to them. This leads to the garage doors always being in a mysterious "Schrödinger's cat" like state of either open or closed.. but which one is it?
Well.. we live in what the Realtor called a "transitioning" neighborhood...  transitioning for the better or worst has yet to be determined. So leaving the garage open for any period of time is like having a free sale on tools, all you can carry!

So, it was either buy an indicator for $35 (which was the wife's choice.. ) or make one with left over stuffs from the bottomless parts box (my choice). The criteria for the project was it had to be as reliable as an off-the-shelf unit and cost $0 in parts. I thought it would take an hour... but like most everything else.. that always turns into a weekend instead.

finished unit.. (just imagine the lights blinking spasmodically)

Digging around the shop I found .. a salvaged roller snap switch, a roll of 24g solid phone wire, a 9v 300mA powersupply from an old answering machine, some perfboard,  some connectors, some scrap wood, recycle aluminum from an old sign, and a Velleman MK102 Flashing LED kit I bought on closeout at the Radio Shack for $2 years ago. One could just use a couple of regular LEDs,  but I wanted something that blinked and wouldn't be overlooked when it was on.

The Velleman kit worked out great since it has potentiometers that allow you to adjust the rate the LEDs flash.. and only consumes 17 mA of power when on. The only modification I did was to solder the LEDs to the backside of the board so they would be able to stick through the holes in the wood box I made for it. The box was made from some leftover pine that I chip-carved in a southwestern motif to match the house... and used a couple of magnets to attach it to the wall.

The contact switch is mounted to a wood block just above the garage door

 a scrap piece of aluminum is screwed to the garage door to make contact with switch when door is closed

Everything connects to a simple perf-board circuit located on the wall just on the other side of the LED module in the house

All in all it works quite well and was worth the extra time I spent doing the woodworking for the LED housing. A bonus is that my youngest one goes crazy when the garage door is open now, running around telling everyone about the "linking light! linking light!".
So I'll consider this a success since it now gives us an added layer of security and I didn't have to make a single trip to the hardware store to finish it.