How did you select your material? Why is it plastic rather than metal? Why is it 1cm thick? Why not thinner? What is its purpose? How precise does it have to be?
To spin it from metal, a form is made (of wood). The form (called a mandrel) is mounted on a special lathe. Then a blank of metal is placed and held against the mandrel while both are spun in the lathe. The metal is then pushed against the mandrel and the metal takes the shape of the form.
Ken
Kenneth Lerman
55 Main Street
Newtown, CT 06470