While you can find giant cardboard letters at the craft store, your options are limited; pre-made letters only come in a small variety of sizes and fonts. Taking matters into your own hands gives you practically limitless possibilities. Creating your own paper mache letters out of cardboard takes longer than simply buying pre-made letters, but it gives you the option of creating letters in different styles and sizes. When you see the finished product---a big letter of your own design and creation---you have the satisfaction of knowing that you created it.
Trace a large letter onto the broad side of an old cereal box. If you do not have one, use any type of stiff cardboard. Cut out the letter with a pair of scissors.
Place the letter you cut out over another piece of cardboard and trace it. Cut it out so you have two large, identical letters.
Cut 2-inch-thick strips out of your extra cardboard; these will make up the middle section between the two letters. Lay the strip of paper on its side and wrap it around each curve and corner of the letter, tape the strip to the letter as you go.
Place the other letter over the top of the strips and tape it into place. The final result is a 3D version of the original letter you drew.
Mix 1 cup water, 1 cup flour and 1/2 tablespoon salt in a mixing bowl. Mix it until it forms a thick liquid free of clumps.
Tear up a newspaper into strips of paper, about 2 inches by 4 inches in size. One by one, dip the strips in your liquid paste and plaster them onto the surface of your 3D letter until it is completely covered.
Allow the letter to dry completely, then apply a second layer of newspaper. Allow the second layer to dry.
Paint the dried and hardened paper mache letter with matt finish acrylic paint.