So here are my renditions Which are not as fancy pants (and probably not as thick as Martha's) but resemble... what they're suppose to. I hope. :]
The first two are hanging out on a piece of cardstock. I figured it'd be easier to "display" them on a card I could write on and explain what they are. Otherwise they might get lost in the envelope! And people wouldn't know what to do with them, since it's kind hard to see the part that lifts up, unless you know it's suppose to do that.
For instructions, see how Martha makes them here. Let me know if you want one from my collection. :]