A forming method that radially compresses hollow rotational parts or tubular blanks via spinning tools to reduce diameter. Workpieces are clamped on a mandrel (solid, composite, or coreless), exposing the forming area. During rotation, rollers follow programmed paths via control modes (CNC/mechanical) to progressively shrink the diameter into waist-drum shapes or closed spherical parts. To prevent wrinkling and cracking, the process is divided into multiple stages based on diameter reduction ratios, with incremental feed per pass. Mandrel swaps,intermediate heat treatment, or heating may apply. Wall thickness in necked zones varies: unchanged, thinned, or thickened, depending on material properties and shrinkage rate. Similar principles apply to hollow part open-end necking, with methods tailored to geometry, material, and quality standards.