[jyl]

Yeah, the middle of the card is wasted space.

That is why i’m thinking the card can actually be two or three separate pieces, and fit together like a jigsaw puzzle to make a rectangular shape.

Suppose it’s three pieces. The first could have 5 mm and 6 mm hex, small flathead and small Phillips, and the middle part could be a serrated blade and a file. The second could have 8 mm and 10 mm, large flathead and large Phillips, and the middle part could be a bottle opener and can opener. The third could have 12 mm and box cutter, with wire stripper notch and not sure what else in the middle part.

All three could fit in a credit card sized sleeve. Or maybe the mating edges could be tongue and groove.

Three credit cards stacked are about 2 mm thick, if steel that should be strong enough to be a usable tool. The little tools that come in a vintage MAFAC bike toolkit are about that thickness and they work fine.