The materials required for this procedure are as follows:
(1) Square sheet of paper, any size is acceptable, larger sizes will be easier to work with. Corners are marked in the image to aid in identification in subsequent steps.
Step 1: Step 1: First Diagonal Fold
Fold the square sheet of paper diagonally, so that two opposing corners touch, and crease firmly.
Step 2: Step 2: Second Diagonal Fold
Unfold the fold made in Step 1 and make another diagonal fold between the remaining two opposing corners.
Step 3: Step 3: Horizontal Fold
Unfold the crease made in Step 2 and fold the paper horizontally as shown.
Step 4: Step 4: Internal Folds
Unfold the horizontal crease made in Step 3, and fold the edges of the paper inwards, as shown.
Step 5: Step 5: Flatten
Carefully press the triangular top face towards the bottom face, collapsing the four smaller side triangles inwards. Take note of the new labeling conventions for this shape, they will be used in subsequent steps.
Step 6: Step 6: Front Corner Folds
All steps on the front face of the triangle are performed with vertical symmetry; that is, all steps performed on the right side of the triangle are mirrored on the left.
Fold the front left and front right corners up to meet the top of the triangle, as shown.
Step 7: Step 7: Front Face Folds
Fold the two outer corners of the new top face triangles inwards to the center crease.
Step 8: Step 8: More Front Face Folds
Fold the top right and top left corners down such that they meet the center line at the same point as the other two side triangles.
Step 9: Step 9: Front Internal Folds
Fold the two small upper triangles created in Step 8 along their longest edge, such that they are folded under the two side triangles created in Step 7.
Step 10: Step 10: More Front Internal Folds
Unfold the creases made in Step 9. Tuck the top right and top left corners inside of the folds in the right and left front face triangles.
Step 11: Step 11: Flatten
Tuck the top right and top left points completely inside the folds and press the front face flat.
Step 12: Step 12: Back Face Folds
Flip the paper over and repeat Steps 6-11 on the back triangle. When completed successfully, there should be a hole in the shape at the bottom point, as indicated.
Step 13: Step 13: Spread Side Folds
Spread the front and back faces apart slightly, then blow sharply into the hole on the bottom of the paper. This should cause the shape to inflate outwards into the completed box.
Step 14: Step 14: Complete
Pictured below is the finished product, an origami cube. The edges can be pinched in order to crease them into a more defined cube shape, if desired.