The Torus is made out of 3/4 inch steel tube, .049 inch wall (18 gauge). You can try using 1 inch diameter tube or other sizes. The important thing is that the center of the tube is lined up with the Hyperbola's Focus. That's where the magic happens.

The circumference of the torus is just under four feet. In the process of bending the tube into a circle on the tube rolling machine, you lose about 10 inches at each end. So order a six foot length of steel tubing.

Low-Carbon Steel Round Tube
0.049" Wall Thickness, 3/4" OD
6 Feet Long
McMaster Carr Part Number 7767T21
$12.66 Each

This is what a tube-rolling machine looks like:

Roll the tube into a circle and weld the ends together. I painted it with Rustoleum protective enamel to keep it from rusting. Now wrap it with cellophane. Then wrap it with a layer of conductive copper foil tape.

I am considering re-working it. Painting the hollow steel ring with a few coats of shellac, lacquer, or epoxy, instead of cellophane. Then wrapping it with copper leaf instead of tape. The copper tape is thick and lumpy. So is the cellofane.

Strictly speaking, this shape is not truely a torus. It is the volume of revolution of an ellipse. But in the real world, pipe comes in circular cross-sections, and it's close enough.