Making your own custom envelope takes only a few minutes. You need a piece of paper that is three times longer than the desired length of the envelop and 2 inches wider on each side, a triangle or a ruler, a pencil, a bone folder, scissors and a glue stick.
Mark the guiding lines
Place the paper on the work surface, and mark the desired size of the envelope on the center of the paper with a triangle or a ruler. Extend these lines to the edges of the paper.
Make the flap
Fold along the bottom line using a bone folder. Cut the bottom flap to make it 1 inch shorter than the height of the envelop. The top and the bottom flap need to overlap. Don't make them too short.
Make the side panels
Take out the extra paper by cutting along the extended lines. Make the side panels about 3/4-inches wide by trimming the corners at an angle.
Trim the top flap
Cut the top flap to a point using the scissors. A scalloped scissors or a French curve can be used to form a decorative edge. Ensure that the top flap overlaps the bottom flap.
Glue the flaps
Fold the side panels inside, and glue them with the already folded bottom flap. The envelope is now ready.