If you have ever designed your own card, only to find that it does not fit the standard envelope, knows what it is like to wish you could make your own envelope. It cannot just be any envelope--it has to look professional, or it will look dorky going through the post office. These are the directions for a 5 x 7-inch card or an A7 sized one. You will not need a template or anything fancy.
Things You'll Need
8 1/2 x 11-inch plain paper
Glue stick or adhesive
Measure the bottom fold by drawing a pencil line across the paper up 3 3/4 inches from the bottom. Do not worry about the line as it will be hidden in the inside of the envelope.
Draw another line across the paper down 2 inches from the top of the page.
Draw two lines on either side in 1/2 inch from either side.
Crease the paper on every line, keeping it as straight and smooth as possible.
Open all the folds and cut out the four outside corners along the lines.
Fold in both sides. Fold up the bottom flap up over the sides and lightly glue along the outside edge of the bottom flap. Smooth it closed.
Insert the card and seal the top flap shut with glue. Your envelope is now ready for the mail.
To adjust this for another smaller size, center the finished card on a plain piece of paper at three inches from the bottom and trace it. Now add 1/4 inch to each side. Follow these same steps using the traced card outline as your reference for the line measurements. For instance, a 4 x 6-inch card will be 1 inch smaller than this 5 x 7-inch one, so you would add another 1/2 inch to the 1/2 inch on either side fold. The bottom flap would be the same, but the top flap would be increased by 1 inch.