You can buy these metal plate and screws from Amazon.
It works really well.
14 1/4" Black Flat Mending Plate Slidable Straps, Straight Steel Straps Repair Plates Brace, Repair Fixing Bracket Connector(Size: 14 1/4" x 1 5/8", Thickness 1/8")
M4 x 15mm Flat Head Socket Cap Screws