I don't know if I'll make these kinds of entries (or videos for that matter) for every card I make, but it feels like a good groove to settle into for a while, so here goes nothing.
This one's got a reverse side. Still not a "watermark" like I'd been planning, but as I'm still using pasted-on bits of graph paper, I guess these don't exactly lend themselves to that style. The "profile" in the upper left is the result of a rubber stamp rubbed along its edge with the brown Sharpie calligraphy pen (then filled in once stamped to help it stand out as it came out very light). I'm not quite sure it works, but it does fit in with the overall concept of the card.
The story goes that Charles Babbage got the idea for using punch cards for his "difference engines" from train tickets that would have details about passengers punched into little tables printed on the stubs. It's kind of a simple genius, really, given that there really weren't photo IDs back then, and not everyone had the ability to forge tickets.