A quick, self-locking fold for an 8.5 x 11 (or A4?) piece of paper.
Resulting size: Approximately 2.5"x4.25" (if A4, 87x105 mm -- I don't have A4 paper, but the math should work like that).

Step 1: Take a blank letter/A4 paper

Picture of Take a blank letter/A4 paper
Blank paper, Portrait
Logan D6 years ago
folding the last tucked in area "in 1/4" and "out 3/4" will create a useful pull tab
spacessj7 years ago
nice, but won't work for an A4 cause it's 210mm × 297mm
crythias (author)  spacessj7 years ago
Your comment doesn't explain enough why this won't work for A4. Because I don't have A4 paper, I tried with 7.777x11 paper (the aspect ratio is equivalent) and obtained a squarish result, but still with a small interlocking tab. To obtain results similar to the above for A4 paper, after the initial triangle fold, make a 25mm (1 inch) valley fold from the bottom rectangle/remainder edge up. This would adjust the proportions to resemble the folds above.
Girls at my school just text on their phones, it's kind of annoying. The guys yell whatever they want to say across the room (it ticks off the teachers to the extreme). I'm gonna use this though, so very nice instructable.
crythias (author) 7 years ago
They were common for me at my school, too, 20 years ago. The problem for me is that I almost forgot how to do it, for whatever reason I needed to do it now, and once I remembered, I thought I'd place something to remind myself how to do it. Thank you kindly for your comment.
These are extremely common in our school. Girls will act like they IM each other xD We have a different way of folding them, but they end up similiarly. Nice Instructable!