So I made this tutorial a while ago for sharing in a spanish website. I found the instructions in a website that I don't remember now (sorry but I made them for last year xmas), but the tutorial lacked of images and it was difficult to follow. So I decided to make my own since it's easier for me to learn with more pictures!
Let's get started
Materials: Paper or cardboard, scissors, ruler or squad, pencil.
Optional: rubber (if you use the pencil only on one of the sides and let that side looking face up there shouldn't be any pencil traces), glue (I didn't use glue for mine since it all stays in it place but if you use a soft paper it might be useful)
Tips: The actual size of the box will be 3 times smaller than the size of the square paper that you start off. A 6"x6" square will result in a 2"x2" box. To make the lid, just make the same box but add 0.5" to all the sides of the square. Box 6"x6", Lid 6.5" x 6.5", and so on. (note the original measurements were in cm and I converted them I hope the conversion is good
Cut a square on the paper. Draw a diagonal line joining two tips of the square.
Fold the tips to the center, using your line as a reference.
Fold in half your square to get a rectangle.
Unfold the rectangle (you'll be in the square from step two) and fold it again like before but in the other direction.
Unfold everything. There will be a little square marked in the middle (I marked it with pencil) That will be the base for your box!
Draw two lines matching two sides of the little square in the middle (they must be parallel). I scratched my lines as soon as they left the square (I hope this has sense!). Cut through this lines without cutting the square in the center (that is why it might be useful scratching it a bit).
Lift the triangular corners (two corners will end up as a triangle, other two as a rectangle with triangle only on the side) Following the folds, fold the tip inside, then you should have a triangle which base matchs the box's base.
Fold the tips inside and then the sides. You will start figuring out that there is a box right there!
Use the fold marks as a reference and fold the flaps left to finish your box!NOTE: I translated myself my original text, It might not be very clear and I am open to corrections!