If you are using a shoebox, discard the lid and skip to the *
1) Remove the entire length and width of the backside of your box with an exacto knife.
2) If necessary, use duct tape to make sure that the interior flaps of the box are not loose or flapping down.
*Flip box over
3) Mark a rectangle on the front/face side of the box with pencil and ruler. Be sure that this rectangle is slightly smaller than the size of your paper and about an inch from the outside edges of the box itself.
4) Use an exacto knife to cut the rectangle out of the face of the box.