Cut out two circular cardboard disks for the top and bottom of your turbine. Measure a 10-by-10-inch square and draw intersecting lines to create four equal quadrants. Where the lines intersect will be the center of your circle. Measure a 5-inch length of string, attaching one end to a thumb tack and the other to a pencil. Place the thumb tack in what will be the center of your circle and pull the string tight. Using the pencil, trace a circle. Use this template to create your second cardboard disk.
Create the wind paddles by cutting four cardboard strips, each measuring 4-by-10-inches. Cut two notches in each paddle. The notches should be three inches long and located one inch from the top and bottom of the paddle. The notches will be used to connect the paddles to the circular disks.
Draw angle lines on each of the cardboard disks. Measure a distance of 2 1/4 inches from the center of your circle on each of the four line segments and mark each measurement with an X. Use a ruler to draw a straight line from the X to the end of the line segment on its right. Repeat for each X and you should have four 90-degree triangles. Darken these newly drawn lines as they will be the locations where you connect your wind paddles.
Double wrap a rubber band three inches from the end of your dowel rod. Stick the dowel rod through the center of one of your cardboard disks, and slide the disk down so that it's resting on the rubber band. Stick the other end of your dowel rod through the other cardboard disk, then double wrap a rubber band one inch from the bottom of the rod. Slide the disk down to rest on the rubber band.
Attach the wind paddles to the cardboard disks. Using the cut-out notches, slide the paddles into place using the angle lines on the disks as a guide. Glue the paddles to the disks to keep them from sliding around.
Stand up the wind turbine. Cut a hole in the lid of a 64-ounce coffee can, just large enough for the dowel rod to fit through. Push the rod through the hole and secure it with electrical tape. Ensure that the bottom disk is free to spin and is not touching the lid of the coffee can.
Test the wind turbine. Set up a table fan in front of it, turn the fan on and watch your Savonius wind turbine spin.