In the Prisma Illya universe, the class cards (cf. below) are physically real magical items. But what about in the "main" Fate universe, where Fate/stay night is set? Do the class cards physically exist there (even perhaps in some non-magical capacity)?
We do see a fair bit of them in the VN, but never "in-universe", per se, at least as far as I remember - we mostly see them as illustrations to accompany explanations given to Shirou, without any actual indication that they are physically present.
I would have thought that the class cards don't physically exist there, but I just had a look at the first OP for DEEN/stay night, and there's a shot there of Kirei holding the cards (cf. video). Not that DEEN/stay night should necessarily be taken at face value, but it does make me wonder.