A bull float is a concrete finishing tool used to smooth the concrete after it has been pressed or tapped down. Professional bull floats can be made of aluminum or magnesium and are meant for long term and continuous use. It is possible for an amateur to construct an inexpensive unit that will perform the same task.
Remove the cloth mop from the mop head, exposing the metal wire frame.
Using the jig saw, cut out a piece of 1/2-inch plywood, 48 by 8 inches. Round the four corners of the rectangle.
Sand the bottom side of the plywood. Remove any rough areas, burrs, or splinters.
Center the metal mop frame on the plywood. Hammer the fence tacks to secure the frame to the plywood. Be certain to tack the frame securely on both long sides of the frame as well as the rounded corners. (Do not allow the tacks to protrude through the bottom of the plywood.)