Ok, but how one make a 2.2m x 2.2m x 2.5m "single-piece steel forging" so the inside cavity can be machined out of the solid. That sounds a great metallurgical

Ok, but how one make a 2.2m x 2.2m x 2.5m "single-piece steel forging" so the inside cavity can be machined out of the solid. That sounds a great metallurgical achievement in this size, allowing the huge piece of metal not only cooling without breaking itself apart from temperature differences of inside and outside but preserving a great deal of streangth too.