Cut two rectangles from the cardboard 2 inches larger than your artwork on all sides. Use the ruler to make the lines straight.
Put one rectangle aside. Draw another rectangle on the inside of one rectangle of cardboard, 3 inches from the edge, parallel to the outer edges.
Use the craft knife to cut out the center of the cardboard on your pencil line, leaving a border around the outside of the cut away rectangle.
Cover the border shape in magazine paper. Wrap one piece of paper around the border shape tightly, covering as much length of the border as possible. Fold the edges of the paper on the back side of the cardboard, overlapping them by 1/2 inch. Secure the overlap with a piece of tape. Apply more pieces of paper, overlapping each piece by 1/2 inch. Continue to apply pieces of paper until the border is covered in magazine paper.
Apply a thick line of hot glue at the top edge of one side of the large rectangle of cardboard, 1/4 inch from the edge.
Press the border piece onto the cardboard rectangle, aligning the sides, and pressing the glue down with your fingers.
Glue the bottom edge and one side of the rectangle 1/4 inch from the edge and press the border down firmly on top of the glue.
Glue one paper clip to the underside of the open edge of the border, the paper clip overlapping the edge of the border by 1/2 inch.
Allow the frame to dry overnight.
Place the artwork inside the frame and bend the paper clip around the back of the frame, closing it.