Water mills are believed to have been invented by the Romans at around the time of the birth of Christ. They harness the power of running water to power anything from millstones to looms for weaving cotton. If you have a stream, you could build a water mill to provide electricity. If you just want a decorative addition to your garden, you can build and enjoy this homemade working water wheel.

Measure 2 feet along the length of one of the plywood sheets. Draw a line across the width of the sheet with a pencil using a carpenter's square to keep it at right angles. Mark out a circle with a 4-foot diameter on the remainder of the plywood sheet and cut the circle out with the jigsaw. Repeat this process with the other 8-foot-by-4-foot plywood sheet.

Measure along the length of each 2-foot-wide length of cut plywood and mark with a pencil at 8-inch intervals. Draw a line across the width at each pencil mark, ensuring it is at right angles. Cut both lengths of plywood into 8-inch sections so that you have 12, 24-inch-by-8-inch sections. These make up the wheels paddles.

Lay one of the plywood circles on a flat surface. Draw a horizontal line across the circle passing through its centre point. Place the protractor on this line and draw a line across the circle at 30 degrees from the horizontal, again passing through the centre point. Place the protractor on the line just drawn and make another line at 30 degrees. Keep doing this until you have divided the circle into twelve segments, each 30 degrees apart.

Apply wood glue along the 8-inch side of one of the 24-inch-by-8-inch plywood pieces. Stick the plywood piece to the circle, along one of the pencil lines, with the 24-inch edge at right angles to the surface. The leading edge of the 24-by-8 should be flush with the outer edge of the circle. Continue attaching the 24-by-8 plywood boards to the circle at each pencil line.

Add glue to the top edge of each 24-by-8 board. Place the remaining plywood circle on top of the boards, making sure it is centred with the bottom circle. Leave overnight to ensure the glue has set.

Lay the rule on the plywood wheel and line it up with the centre of a paddle. Draw a pencil line 24 inches long, marking the position of the paddle. Move around the wheel, marking the position of all of the paddles. Turn the wheel over and mark the positions of the paddles on this side.

Drill 4 pilot holes along each pencil line at 5-inch intervals from the outer edge of the wheel using a 1/32-drill bit. Turn the wheel over and drill pilot holes in the same way. Insert 4, 6-inch galvanised screws into the pilot holes and drive in with an electric screwdriver. Coat the whole wheel with waterproof wood sealant.

Drill a hole at the centre of the wheel using a 1-inch wood bit. Align the hub plate so that the axle hole is in line with the drilled hole in the wheel. Fix the hub plate to the wheel using 1-inch, self-tapping screws. Drill the opposite wheel face and fit the second hub plate in the same way.

Mitre the corners of each piece of 4-by-4 at 45-degree angles using the table saw. Screw one of the 4-inch pieces to the ends of two, 36-inch pieces to form a "V" shape. Construct a second "V" shape in the same way. Turn the "V" shape upside down and screw one of the feet to the 5-by-2 timber lengths at right angles. Screw the other foot to the other 5-by-2 timber at right angles. Fix the second "V" of timber to the 5-by-2 planks opposite the first to complete the frame.

Screw the bearings to the tops of the frame exactly opposite each other. With help from a friend, position the wheel in the frame and slide the axle through the bearings and the wheel. Tighten the locking nuts of each hub plate to secure the axle. Adjust the locking nuts as necessary to ensure the wheel rotates evenly.