Things You'll Need
Cardboard box (new or used)
Box cutter or scissors
Cutting a cardboard box to a custom size provides a tighter fit for the items within while minimizing the need for excess packing materials that may result in a larger shipping fee if you intend to mail the box to a friend or customer. If you are a frequent seller on Ebay or if you need to pack a present for a friend or a family member, then customizing the size of your cardboard box is a convenient skill to learn. You can use a new cardboard box or an old box that you'll turn inside out to hide the previous shipping labels and packing tape.
Open the cardboard box to lie flat on its side on a table or other flat surface.
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Find where the cardboard was glued in place to create a box. Most cardboard boxes are manufactured from a single piece of cardboard and one end is folded to glue onto the opposite end. This is often located near one of the corners of the cardboard box. Pry apart the two ends of the cardboard box so you can work with the single long piece.
Place the items that will go into the cardboard box near one edge of the flattened cardboard. Leave enough space between the items and the edge of the cardboard so the edge will cover the side of the item when you cut the cardboard.
Mark the outline of your custom box in pencil around the item on the piece of cardboard, accommodating the space you'll need for the top, bottom and side edges of the box. Mark an outline that is the same shape and size of the first outline, minus the side next to it, next to the first outline. The total outline should be the size of your custom cardboard box if it was laid flat.
Use a box cutter or scissors to cut the outline for your custom cardboard box.
Fold up the edge of the cardboard on the vertical side where the item was initially placed.
Fold up the opposite edge of the cardboard to create a similar edge on the other vertical side of the item then fold the excess of this opposite edge of over the item to create the box. Use packing tape to affix the two edges of the cardboard.
With the items centered in the custom cardboard box, make vertical cuts at the top and bottom ends of each side of the cardboard to create tabs that will allow the excess cardboard at the top and bottom to act as flaps that will fold shut over the items.
Fold the cardboard flaps shut over the items and seal the edges with packing tape to close the box.