You can make your own cardboard boxes at home with ease, using tools and materials you probably have around the house already. Thinner cardboard is easy to work with, and good for craft projects. If you are shipping items, corrugated cardboard is the way to go; it is much stronger and meets most shippers' requirements for self-packed items. For fragile items being shipped a double box (a box within a box, separated by packing peanuts or other buffer) is recommended. You can get double-thick corrugated cardboard for extra strength as well, available from packaging suppliers.
Decide on the length, width and height of your box. Lay out your cardboard on a table or the floor, and measure a rectangle in the middle of the cardboard towards the top end in the dimensions of the length and width and draw the rectangle. Use a T-square to keep the angles square. This is the bottom of the box.
Lay the straight edge along one of the edges of the bottom of the box and extend the line out the distance of the height of the box. For instance, if your box is to be 8 inches high, extend the lines out 8 inches in each direction from the bottom of the box.
Repeat for the other three sides of the bottom of the box.
Draw a straight line attaching the ends of the lines on each side, creating four new rectangles attached to the bottom of the box. These are the sides of the box.
Draw a rectangle the same size as the bottom of the box attached to the side lowest on the cardboard, creating a T-shape on your cardboard. The bottom of the box is in the centre toward the top, the sides of the box are connected to the bottom of the box (one on each side) and the top of the box is connected to the lower side.
Use your straight edge and utility knife to cut out your box.
Use your utility knife and straight edge to score the lines between the rectangles. Cut part way but not all the way through the cardboard. This will make it easier to fold.
Fold the sides of the box up and tape along the seams. Fold the top over to close the box.