Save the corner pieces, they will make your Knuckle spacer at a later stage of construction. Now to attach the first protective edging to the shield blank. Any metal edging material will improve the life of the shield. Clip the slit open hose around the perimeter of the shield. Check the dumpsters at your local bicycle repair shop.
Reasons are mostly cost.
Cut the tire so that the circle is broken. On a heater shape, the joins are at the rear top angle and at the point of the heater. With a washer on the bolt, insert it from the front of the shield. At the rear place the other washer on, then the nut, and screw down tight. If the shield is heater shaped, it has to be balanced.