Cut two 60-inch lengths of the 3/4-inch electrical metal tubing. Measure 8 1/2 inches from the end of each and mark. From the same end measure and mark 20 1/2 inches, 47 1/2 inches and 53 1/2 inches. Use the conduit bender to bend each piece to a 35-degree angle at the 8 1/2 mark. Bend the 20 1/2 mark to a 35-degree angle in the opposite direction to form an "S' shape. Bend the 47 1/2 mark in the same direction as the 8 1/2, and the 53 1/2 mark in the same direction as the 20 1/2.
Assemble your handles. The length of pipe above the 8 1/2-inch mark are your handles. Snuggly fit a bicycle grip over each pipe.
Make your spades. Cut the 4-inch electrical metal tubing in half so you have two 3 1/2-inch pieces. Cut each pipe vertically open in a straight line and use the conduit bender to open each pipe into a semicircle. Draw a rounded edge around the bottom of each piece and use your saw to cut along it. Cut four small triangles into the bottom of each piece to form teeth.
Drill a hole half way between the 47 1/2 inch bend and the 53 1/2 inch bend in each pipe. Use your 5/16 machine bolt to connect the two pipes together so that they face each other symmetrically.
Attach the spades. Drill two holes vertically in the top of the spades 1 1/2 inch apart and drill corresponding holes into the bottom of your pipes. Join each spade to its pipe using the carriage bolts so that they are facing each other.