We love easy paper crafts and this is a great Eas. 7 août 2020 · 1 rectangular sheet of paper, such as A4 or letter paper Instructions Determine the Right Paper Size You will need one sheet of rectangular paper such as A4 or letter paper. For example, an envelope made with 21 x 29.7 (A4) will fit small paper that is about 8 to 10 centimeters.