Cut four pieces of pre-mitered wood frame using the measurements of the backsplash piece you wish to frame. Glue and staple the four corners of the frame together. Shoot the staples into what is normally the front of the frame. Turn the frame around so the back is now the front.
Nail a hanging hook to the back of the frame with finishing brads.
Cut a piece of 1/4-inch wood backing to fit the mitered insert in the frame. Glue the metal backsplash sheet or series of tiles onto the wood backing with tile mastic adhesive. Allow it to dry overnight. If you are using a single metal tile, you do not need to glue it onto a backing.
Draw a line of caulk around the mitered inset in the wood frame. Drop the glued backsplash and board into the frame. Hang your metal backsplash as wall art.
Cut four pieces of 1-by-2 lumber with 45-degree angle edges to form a 2-inch-deep frame. Use the measurements of the metal backsplash sheet or series of tiles to determine the measurements of the inside of the shadow box frame. Glue the box frame together with wood glue.
Cut a piece of backer board that measures the same as the outside of the box frame. Nail the backer board to the back of the frame with finishing brads. Nail a hanging hook to the backer board with finishing brads.
Glue a metal backsplash sheet or a set of metal tiles to the backer board on the inside of the box frame with tile mastic adhesive. The backsplash installation will look sunken into the frame. Allow the backsplash art to dry overnight. Hang the backsplash as wall art.