These are some of the buttons found for the trigger. I still vote for
the if you stick something-up-the-tube-it-goes-on trigger but this
gives us options.

I like red buttons – but red buttons can mean STOP or Emergency STOP!
In certain contexts. Don’t know if that matters. The Illuminated
buttons allow for custom art, now and in the future.

ADA Door Style:
http://www.alibaba.com/product-gs/279657574/LARGE_SIZE_EXIT_DEVICE_PUSH_BUTTO…
http://www.disabilitysystems.com/switches/

Jumbo Domes:
Illuminated: http://na.suzohapp.com/pushbuttons/954002xxxxz.htm
Not Illuminated:  http://www.arcadespareparts.com/arcade_parts/push_buttons/arcade_button_jumbo… 
More Illuminated (Green?): http://www.arcadespareparts.com/arcade_parts/push_buttons/arcade_button_dome_… 

http://www.sparkfun.com/products/9181

MISC:
Button Manufacturer (for sale on DigiKey) (largest only seems 2 in?) http://www.apem.com/pushbutton.html
Touch Pad Switch and Other Interesting Options: http://www.mcmaster.com/#touch-pad-switches/=dolfvl
Big Red Emergency Stop Button: http://www.grainger.com/Grainger/LOCKNETICS-Standard-Push-Button-1RAD8?Pid=se…