...and then I found marble magnets! (see Mormon Chic, Quidnunc.org, and NotMartha, et al.)
So I did a test run. As it turns out, my graphic design skills are seriously lacking. But here's what I came up with. I'm still not sure if it's worth including with the save-the-dates or not. They are way easy, so that's not a problem, at least. I'm just not sure if they are pretty/cool/neat enough to make it worth including. I guess I have to decide sometime this week, because I should be sending them out by this time next week!