I used to fold up this piece of paper into a square, then at one end was a small hole. If you blew pretty hard in this hold the square would inflate, and you would be left with a 3D cube. Can anyone point me in the right direction?

Yes, this is made by starting with something called the "Water Bomb Base" and the piece you're looking for is the "water bomb" itself. If you go to this web page, you'll have the directions. I think the page itself is in Czech, but the directions are very clear. Good luck!

http://www.origami.cz/Bin/bwaterbomb.gif

Thank you so much. I got most of it, then got stuck with those pictures. But the name of it, I was able to google, and found a site in English that I could follow. Thank you again for helping!!!!!

My pleasure - Happy folding!

This is one of the classics of origami. I often make these with different size pieces of paper to get different size boxes. They are called water bombs because you are supposed to be able to fill them with water and then throw them!

As a youngster, We would draw pictures on the part of the paper that would be the inside, fold it up, and we'd trade them...you blow it up and look through the hole to see the picture. Would be a great advertising gimmick if you could make the text (and whatever pics) inside look professional.

Steve

It's called a "WaterBomb and most Origami Books have this. I first saw it in a book on Origami by Dover Pubs. It is made from a waterbomb base (go figure). I have it on my DVD, Money Menagerie. You can also with minor modifications make the WaterBomb (cube) into a rabbit.

Hope this helps.