Place your picture frame face down on a flat surface. Place the canvas face down inside the frame.
Place offset clips (bent clips that adhere the frame to the canvas) on the edges of the frame with the screw hole resting on the frame. Place the clips on the top and the bottom of the frame, 2 inches from the corners. Position the solid end of the clips (the end without a screw hole) over the edge of the canvas.
Drill short screws into the frame through the hole in the bent clips. Tighten the clips down so they don’t rotate under the screw. The clips hold the canvas on the back in place while the lip at the front of the frame keeps it from falling forward.
Examine the edges of the artwork to determine how much room you can devote to the frame. For example, determine if you can cut a half-inch off each side of the image without ruining the integrity of the design. Draw a faint pencil line around the edges as a reminder of where your frame should sit.
Cut a square out of a piece of mat board. The square should be the size of the artwork after you subtract the distance of the outer edges.
Cut four pieces of tape 2 inches in length. Bring the edges of the tape together, forming a tape loop with the sticky side on the outside.
Press the tape loops flat on an uncut piece of mat board that is at least 3 inches longer on each side than your artwork. Position the loops so they will sit where the outside edges of the artwork sit against the mat board.
Press the tape loops flat on an uncut piece of mat board that is at least 3 inches longer on each side than your artwork. Position the loops so they will sit where the outside edges of the artwork sit against the mat board.
Set the cut piece of mat board on top of the artwork. Line up the edges of the frame with the lines on the artwork. Press the corners down to make the putty bind the front piece of mat board to the back piece.