But envelopes can get expensive, and I often don't have them on hand, or don't have the correct size. This instructable will show you how to fold your letter into its own envelope, saving you ( tens of ? ) dollars and maybe some time.
Step 1: You'll Need...
You'll need a letter. This folding works best for letters written on 8.5' x 11' or A4 paper, or similar. Letters written on substantially larger or smaller sheets of paper will likely have trouble conforming to U.S. Postal Service letter size requirements.
Step 2: Initial Folds
Keeping the letter horizontal, the next step is to fold the lower left corner up and to the right 45 degrees, such that the left edge of the fold is parallel with the reference crease but separated by a gap of about a half an inch . This is a rough estimate as I never measure the gap width, but a gap like this will help our envelope conform to USPS letter size requirements (they like letters that are a bit longer than they are tall, as they are better for machine processing). An example of the type of gap is marked with a green dotted line in the photo above. [Pic. 2]
Next, repeat the previous fold in reverse with the top right corner, again leaving the half inch gap from the reference fold. [Pic. 3]
Step 3: Secondary Fold
Rotate the letter 90 degrees so it is oriented the tall way again (portrait). Take the upper right-hand edge of the letter and fold it to the left, keeping it parallel to the original edge, and again leaving about a half inch gap from the edge of the triangle made by the previous folds. I've marked the approximate line you should fold to in green. [Pic. 1 & 2]
Your letter should now look like Pic. 3.
Step 4: Tertiary Fold
Step 5: Repeat, Repeat
First fold the lower left edge over until it is flush with and perfectly covers the flap made by your last fold in step 4. [Pic 1]
Then fold the lower left corner up towards the reference line (in red), like you did in step 4, but this time making sure to tuck it into the tab along the right edge of the letter. [Pic 2]
Your letter should now look like this [Pic. 3]. The tabs keep the letter closed. However, I would suggest putting a piece of tape across the middle if you will be sending it via USPS, as their machines (or mail carriers) might cause it to open otherwise.
Step 6: Your Done!
Hopefully now you will be inspired to go and write a letter of your own. It really is a great way to pass some time on the bus or in the dentist's waiting room, and as I mentioned everyone loves getting real mail.
This is the first of several postal-structables I hope to upload, as well as my first instructable ever, so any advice or questions are very welcome!
Go forth and Mail-tiply!
PS. Here are some other postal-structables I've made: