For this project you can actually use any type of card or paper...Even old greeting cards, thank you cards, etc can be recycled in this way. It is also a project you can do with kids, who usually love to punch holes :) or even older kids who know the basics of crochet.
You will need:
Yarn of colour you prefer for the project
These are very basic, but there is so many possibilities!! Cotton white thread on white cardstock could be very pretty for special occasions... especially with a more intrincate lace trimming...