Then I glued a piece of colored card stock to the white card stock.
Take your iron and ironing board. Plug in the iron and set it to the "Wool" (medium) position, without steam.
Prepare a sheet of baking parchment, a piece of cling film and your napkin card.
Place the cling film on the card.
Work in an airy space, as heating the cling film will certainly produce unnatural fumes...