The Torsion-Ring Spin Rig — A Room-Temperature Build Package for Blueprint Unknown #15 (R&D Division Package A2)

A build package for a bench rig that spins a dummy aluminum torus inside a transparent surrogate vessel at room temperature, instrumented to measure ring-center offset against speed — grading the drive/bearing concepts entered for it (shaft-driven and magnetic-coupled to be spun; a third, roller-supported concept was killed on paper in the package's own Round Table review, and its failure analysis is included) against pass/kill lines registered before any spin. The rig attacks Unknown #15 (ring mounting/bearing) of the torsion-ring plasma container blueprint (Rev C, DOI 10.5281/zenodo.23802958) in the only regime where iteration is cheap: room temperature, ordinary materials, local fabrication. The grades, printed at full size on the package itself: this is a paper design study — nothing has been built, spun, or measured. Buildability A (as revised in the package's own Round Table pass, included). Claim grade: mechanical feasibility only. Of the three bearing/drive concepts entered, one was killed on paper by its own geometry before any spend — its failure analysis is printed in the package. The rig cannot answer behavior at 4 K, in vacuum, with the real ring material, or in plasma — its unknowns table prints all of it — and it neither supports nor refutes the parent design's torsion-centering claim, which remains asserted, not shown. All costs are by vendor quote; no price is printed that a vendor has not quoted. The parent research program's headline is unchanged and is not advanced by this package: vacuum catastrophe NOT SOLVED / PARTIAL, producing-count 0.