For the creation of cylindrical hollow ( metal ) shapes one can use the centrifugal casting or centrifugal moulding technique. The technique makes use of a mould that exists out of multiple section that together form a shell describing the outer surface of the desired product. The mould needs to be constructed in such a way that it can be removed from the product without damaging of deforming the product. Separate cores can be used to create undercuts and holes in the product.
When the mould is assembled and closed firmly, a defined amount of molten material is casted into the mould while it is spinning around its axis. The centrifugal effect forces the material against the outer wall of the mould forming the hollow shaped product. Once the material is cooled and set the product can be removed from the mould starting the proces all over again.