In order to evaluate Stretch Form feasibility, the cost model first determines which of the two Xsection GCDs (see Xsection GCDs) has the greater curve height (see Xsection Curve Height for Stretch Forming). The Xsection with the greater curve height is referred to as the transverse Xsection; the other Xsection is referred to as the longitudinal Xsection.

The cost model always evaluates the feasibility of both the transverse routing and the longitudinal routing (see Routing for Stretch Forming).

Transverse stretching is feasible if a sufficient fraction of the transverse Xsection curve is in contact with its associated hull. Similarly, longitudinal stretching is feasible if a sufficient fraction of the longitudinal Xsection curve is in contact with its associated hull (see Xsection GCDs).

A sufficient fraction of the curve is in contact with the hull if the ratio of the GCD property Hull Overlap Length to the GCD property Curve Length is less than or equal to the cost model variable allowableHullToCurveRatio (0.8 in starting point VPEs):