Use grid 80 sandpaper to remove every rust and dirt from the shovel. Try to remove most of the paint. If you have a sandblast machine… you’ll save a lot of time.
I can’t really give you specific dimensions for the metal plate holding the light socket since most shovels are different. Basically, all you will need to do is punch a hole, 4.5 cm wide, in the steel foil and cut a V-shape to fit the shovel’s shape. Bend the end of the V to create a surface that will help you stick or weld the two parts together.
3)Check up and Paint
Make sure all the components fit together. Screw the socket on the plate and make sure the light bulb doesn’t touch the metal. If everything works fine, remove the socket and paint everything with heat resistant paint (BBQ paint).