Determine the size of the artwork to be framed. Measure the height and width before cutting the mat. Allow for 1/4-inch overlap around the artwork or picture, and deduct the measurement from the height and width of the picture size.
Make extra considerations if you are framing the mat. Measure the height and width of the frame, and calculate how much room you have left for the mat between the picture edges (including the 1/4-inch overlap) and the inside of the frame. A good rule of thumb is to allow at least 3 inches for the width of the mat.
Using the artwork dimensions, mark lines for cutting on the underside of the mat with a ruler and pencil. It may be helpful to make intersecting marks at the corners before drawing guidelines for the edges. Check the measurements with a ruler at intermittent points on all four sides before cutting.
Cut the mat on all four sides using a utility knife or mat cutter. Remove the center piece and set aside (you will not need the mat center, but you may choose to save it for another project). Cut the second mat smaller than the first, repeating Steps 1 through 4. The width of the second mat will be smaller, but how much depends on your taste.
Apply the adhesive transfer tape to the back of the smaller mat. Position the smaller mat over the top of the larger mat, and press down to affix. Lay the mats face-down and center the photograph or artwork on the mat opening, with the front of the picture face-down over the mat.
Make the T-hinge that affixes the artwork to the mat by placing two pieces of tape vertically at the top of the picture, about 1 inch away from the corners. The tape should be half on the mat board and half on the back of the picture. Place two more strips of tape horizontally over the top of the vertical pieces to make a T-shape. You do not need to tape the bottom, as the picture should be left free-hanging to prevent wrinkles. Your artwork is now ready to frame or to hang.