How to Make a Spun Aluminum Toroid

Locate the center of a square sheet of aluminum by drawing a pencil mark from opposite corners with a straight edge.

Mark a circle on the aluminum with a compass, using the center-mark. Use a pencil compass, or just lightly scratch the circle into the aluminum.

Cut out the circle with a pair of shears. Sand or file the edges so there are no sharp burs or edges.

Drill a small hole in the center of the aluminum disc and mount the disc to the spindle of your aluminum spinning machine. Depending on the scale of your toroid, you can use a specialty spinning machine, a lathe, a vertical mill or even a drill press.

Press against the back side -- the side to be concave -- of the aluminum sheet with a spoon-like steel tool. You can use any steel tool that's a convenient size that has a spoon shape. Or, if you're doing a lot of spinning, your could grind your own with an angle grinder and progressively finer flap sanders.

Press against the opposite side with a smaller diameter spoon tool, not quite at the same point as the large diameter spoon. Similar to pottery, slightly offset pressure from each side of the material will form the aluminum.

Shape the contour by slowly moving the larger spoon up one side, applying pressure, while pressing against the other side with the smaller spoon. You'll see the aluminum bend immediately in response to the offset pressure from varying diameter tools; the initial feed back of the aluminum will show you how to shape the toroid, with the smaller diameter spoon, directing the curve.

Form two half toroids, then trim away the excess in the centers and the outsides. They can be joined with rivets, or even TIG welding.