Design concepts, manufacturing steps and calibration strategies of a large ring segment are reported in this contribution. The study aims at investigating the feasibility of using a ring segment for establishing the traceability of large diameter workpieces, primarily to quantify the influence of the workpiece surface and form. The ring segment embodies two nominally coaxial features: a cylinder and a torus. Both the cylinder and the torus are highly partial features, which poses a challenge for the calibration. The measurands to calibrate are defined in terms of intrinsic and location features, according to the model for geometrical specification and verification (EN ISO 17450-1). The adopted measurement strategies are described and preliminary calibration results are reported.