You need: A square piece of coloured card or an old greetings card (front and back)
A Ruler, a pencil, some scissors or a scalpel.
Find an old Christmas card and cut off the front page and put aside the back. Crop it to a square shape (if not already). Try to use a card larger than about 12cm square otherwise your box will be very fiddly and small! The finished box will be about a third the width of your card size. You can use any sheet or card if you want to or a large piece for a bigger box.
Draw a line from corner to corner on the back of the card (dont worry this wont be seen) and then from the other corners. There shouldn't be any need to measure anything on the card. Now that you have found the middle of your square you can draw a vertical and a horizontal line. Draw from the corners of these lines some vertical lines, carry on until the back of your card looks like that of the photo.
Now cut and score the lines as shown in the image, using scissors or a scalpel
Fold the corner triangles backwards. Then fold the two that are on the square sections into the middle. (you can fold them back again in a minute).
Fold other sides into the middle as shown. Tuck the triangle edges inwards.
Fold the square sections over the top of the tucked in bits and the top of your box is ready. There should be no to stick it but you can if you want to. Repeat the whole process again using the back of the card to make the bottom of the box. It's a good idea to make the square in stage one a little smaller so that your finished bottom half will fit inside the top. Now you have a festive gift box and you can make any size you want!