You will need 16 brackets. They are called Stanley
corner braces ( 2 inches ) There are two brackets in
each package and they cost almost $3 per package.
Screw each bracket into the sides of the 5 metal
panels. You will have to puncture the sides of the
sheet metal with something sharp like a nail and
pre-drill the hole before screwing in the screws.
Make sure the brackets are even with the surface
of the sheet metal panels. The screws that come with
the Stanley braces are only 1/2 inch long, to make
the pad stronger, don't use these screws and use
screws that are at least 1 inch long.