To make a waterfall card you will need an 8.5"x 11" piece of card stock and a standard a1 sized card.
Print the pattern for the card and cut one out of the card stock, along all solid lines. A simple way to do this is to use temporary glue to hold the pattern to the front of the card stock, and cut the pattern and the card stock together. Score on all of the dotted lines, and mountain fold each score.
