This is an Origami cup. It is a very simple and practical design with only 5 folds. With a little practice it can be done fairly quickly.
This is my first instructable so bear with me and please leave comments.
●Square piece of paper (preferably wax paper)
One last thing to keep in mind before you start, when choosing the size of the paper, use the last picture above as reference. The cup came from the same size paper as the blue page.
Step 1: Fold 1
First, take paper with back side up (if there is one) and fold diagonally as shown. Make sure the crease is flat.
Step 2: Fold 2
Take your triangle and bring the lower right corner up to the left side as shown. The new horizontal line should be parallel to the bottom. Make sure the fold is flat.
Step 3: Fold 3
Now, flip the piece over and make a fold similar to the last one: Take the lower right corner and bring it to left point as shown. Again, the new horizontal line should be parallel to the bottom.
Step 4: Fold 4
This step is a little more tricky. Open up the pocket created by the last step (shown with my left hand in the second picture). Then take the front flap on top and tuck it into the pocket (picture 3). Try to have as little of that flap showing as possible and press flat.
Step 5: Fold 5
Flip piece over and repeat the last step.
Step 6: You're Finished!
That's it! This design is completely watertight, especially if you use wax paper (which I didn't).