The punch I talked about earlier just came in, and I'm thrilled. It's exactly what I was hoping for: something to make a neat, V-shaped notch in the edge of my homemade edge-punched cards:
The red overlay shows the sizes of the punches I've tried and how much paper they remove. The first one was too big. The second one was too small. But the third one? Just right. Zsa Zsa, my Studio 44 is home this weekend for a touch of case repair, so she helped me type up cards for the remaining ideas that I'd jotted down over vacation. I was concerned about running the perforated edge down into the works of a typewriter -- visions of the line of holes being chewed up -- but I needn't have worried: Zsa Zsa offered a gentle touch and was most well-mannered.