Measure the length and width of your artwork and cut your mat to the desired size or use a precut mat. Mats are usually cut with a slightly thicker bottom, but you can personalize the mat however you like.
Center your artwork in the window and flip the mat over so that the drawing and mat are face down. Neatly cut three or more 1-inch pieces of tape. Never use Scotch tape, masking tape, duct tape or packaging tape -- only use acid-free tape. Any acid in your tape, paper, mat or backing will cause the artwork to discolor over time. If your artwork is on lightweight paper, use clear artist's tape so that it doesn't show through from the front.
Place the first piece of tape in the center of the top to adhere the drawing to the mat. Add more pieces close together on either side of the center piece of tape until the top of the paper is securely adhered. Only tape the top of the artwork, not the sides or bottom. Your artwork will stretch and shrink in different levels of humidity and temperatures. Taping all sides will cause it to buckle or wrinkle in the mat.
Place your backing material on top of the back of the drawing. Use acid-free cardboard or foam core that is slightly smaller than the length and width of the mat.
Cut two neat pieces of tape that are about 2 inches shorter than the length of the backing. Place each strip in the center of the length, securing the backing to the mat so that the tape doesn't touch the artwork. Cut two neat pieces of tape that are about 2 inches shorter than the width of the backing. Secure the width sides of the backing to the mat. Smooth out any wrinkles in the tape.