What I do is just use a proxy, preferably one that's similar to my fan card (both flavor-wise and function-wise) so it's easier to remember. If I ever develop my cards to the point where I want them in full physical form (or decide to print out someone else's), I'll probably print them on paper and sleeve them with the extra basic cards behind them (thus far, I've only made physical copies of fan events, primarily because it doesn't matter if they're distinguishable from the official ones since you don't need to mix them into your deck).
By the way, does this belong in the Variants & Fan Cards subforum?