For all of you who are betting on a card to mass-produce inexpensively, let your kids shuffle up a pack of these, and their valentines will love the hands they've been dealt.
Use a pencil to trace around a playing card onto card stock, then cut out the traced shape.
On one side, write the letter A on 2 corners as shown (make one A upside down, as on a real playing card). Decorate with heart stickers and add a message like "You're a real Ace" or "You're an Ace in my book." On the other side, write who the card is to and from.