When folded, this "card" is 2"x3".  Make covers from colored trading card sized cardstock (2.5"x3.5").  We think this would be great as a unique foldout on a regular sized card.  Just paste this folded mini card on top of a standard A2 sized card (4.25"x5.5" folded).  Then, stamp a trading card and paste it on the folded mini card.  Keep the mini card folded with a paper latch or a ribbon.  The folded card would be great space for signatures, a surprising "Happy Birthday" or similar greeting or for a favorite long poem or other writing.