Mitered Corner 1x2 Frames

Cut the four inner pieces to 12", mitering both ends at 45°.

Cut the four outer pieces to 13-1/2", with a 45° bevel on both ends. Mark the pieces to keep track of which side faces out before you move on to assembly.

Dry-fit all four inner pieces first to confirm the miters close cleanly at every corner. Once satisfied, nail through each corner into the perpendicular board to form the inner frame.

Nail the outer frame's corners together the same way. Then nail the outer frame to the inner frame, keeping both frames' faces flush and aligned.

Sand all edges and corners smooth, then paint or stain as desired.