Create the outer frame by laying the two 58-inch studs on their narrow sides on the floor and placing two 30-inch studs between the ends of the 58-inch pieces. Nail through the 58-inch studs into the ends of the 30-inch side pieces with the 3-inch nails so they are well-attached.
Nail the other two 30-inch studs to the inner portion of the frame about 14 inches in from each side, creating a box frame with two inner rails.
Place the first piece of plywood squarely on top of the frame and nail it to the sides and rails of the frame with the 1-inch nails.
Attach a shock mount absorber such as found in Resources at each corner of the plywood and directly in the center. Many shock absorbers screw onto the base with standard screws.
Place the second sheet of plywood on top of the shock mount absorbers and drill holes though the wood to allow you to insert the proper screw into the top of the shock absorber. Screw down the top lay of plywood.