1. Draw or trace a letter on the foam board, then cut it out with a craft knife. Secure the end of a piece of yarn to the back of the letter with a piece of tape or a dot of hot glue.
2. Start wrapping the yarn around the letter's vertical edges. (Some letters, like O, won't have any. Every letter is different.) Push the yarn to the edge as you work. Continue wrapping.
3. Keep wrapping until all the vertical edges are wrapped.
4. Tape or glue the end of the yarn to the back of the letter. Starting from the bottom, wrap the yarn horizontally around the letter and work your way up.
5. Keep wrapping the yarn up the letter form. When you reach the top, cut the yarn and then tape or glue the end to the back of the letter.
6. Start from the bottom with a new piece of yarn and continue wrapping.
7. Continue wrapping until the letter is completely covered. Experiment as you go to make sure any curves are wrapped so they look finished. (Hint: Letters with straight edges are easier to wrap!)
8. When you're happy with how the letter looks, be sure to tuck, tie, tape, or glue the ends of the yarn on the back. Attach a piece of yarn to the back of the letter as a hanger.