Card blanks are especially useful for quick cards and batches of cards. Wedding invitations, thank you cards and Christmas cards can be made in no time at all with a few simple embellishments and a pack of card blanks. If you are using heavy embellishments on your card be sure to choose a thicker card blank. The thickness of card blanks is measured in the weight of the cardstock; it is the weight of one square metre of card in grams (gsm). Always check the gsm when buying card blanks as the higher the gsm, the thicker the card.