If you have two equally sized pieces of cardboard, it takes just a few minutes to make a gift box. The cardboard does not have to be blank, as you can recycle flat pieces of cardboard from cereal boxes, greeting cards, or other sources to make gift boxes. The size of the cardboard sheets and folds determines the box size. Two sheets of equally sized cardboard pieces make one thin, wide box, or one narrow, deep box.
Determine which of the two pieces of cardboard will make the actual box bottom, and which will be the box top.
Trim the box bottom piece by about 3 mm (1/8 inch) along one end, and one side. The box bottom needs to be slightly smaller than the box top. Use a straight edge and box cutter to make a straight cut.
Lay the two pieces of cardboard upside down in front of you on a flat surface. The visible sides of the cardboard are the sides making the inside of the box.
Fold one edge of the box bottom piece over, making a crease along one side of the piece, that will be the depth of the box. For example, if the finished box is to be 5 cm (2 inches) deep, make a 5 cm (2-inch) fold along one edge of the piece. Run the side of a ruler over the fold to make a sharp crease.
Unfold the fold and turn to an adjacent side of the piece, folding it in an identical fashion and with the same measurement. Repeat, until the cardboard has creased folds along all four sides. Repeat with the other piece of cardboard.
Look at the corners of the cardboard pieces and note the square creases in each cardboard sheet. Use the scissors to cut along one side of each square, cutting from the end of each piece, to create four corner tabs on each sheet of cardboard.
Bring the folded sides up on the box bottom piece, forming the box bottom. Tuck each corner tab into the interior of the box to hold in place, and secure with tape. Repeat with the box top piece. When finished, turn the box top over and slip atop the box bottom.