Box 1 Switches?

[hapki]

I have a Box 1 on the way. How do ya'll build switches into Box 1? I saw one ideal on the recent "Everything Switches" discussion, but that's beyond my smithing abilities. I think I remember someone saying the cards were flexible enough to lay over a switch, so that pressure on the card activates the switch. Now I can't find that post. (And searching Box 1 doesn't get me far.)

Any other ideas?