I had the idea of getting a big "panic" style push button from Halted... But then I remembered lots of folks on the Internet seemingly have made effective and hilarious use of the Staples "Easy" button.
As it comes (for $5.99), it has a very loud tactile click mechanism inside and when you push it, a little voice says, "Well, that was easy."
If you take a more... holistic... look at what you get for your $6...
- A 2x AAA battery holder
- A speaker
- A button
- some weights to make the thing more stable in a table-top configuration
Not a bad set of capabilities.
But for this project, all I wanted was the button.
I had started down the road of getting it working, but was having trouble with getting the switch to actually work, so Mark McCrate came by and we collaborated to finish it.
But I don't want to leave it there.
The difficulty I had was in "editing" the PCB that was in the button to get access to the switch. I think for the good of hacker-dom, we need to make it easy to replace the entire PCB.
What I have in mind is an Eagle "easy button" library.
It would be similar to the Adafruit shield library - it would have the outline of the maximal round PCB that will fit in the allotted space, along with the conductive switch footprint for the button contacts, and with all of the holes required to mount the board in place of the original board. Add the part to your schematic, and you just get a switch. On the board layout, however, you get the whole shebang.
There ought to be plenty of room to even add a through-hole ATMega328 if you wanted to, though surface mount parts would be more apropos. And, of course, you've got 3 volts (or so) from the batteries and a speaker to play with. What more could you want?