I'd strongly recommend making them yourself. Everyone understands these things differently, and ideally your cards will complement the structures already repres

I'd strongly recommend making them yourself. Everyone understands these things differently, and ideally your cards will complement the structures already represented in your own mind. Ideally, a card will shine light on one tiny aspect of the model you already have in your mind; if you're using cards shaped around a different model, and you drop them into place around your own model, the lights may be at strange angles or highlighting big complex things.