This 2D companion plots the same three constitutive stress-stretch models as the 3D version — Neo-Hookean, Mooney-Rivlin and Gent — on a flat Canvas2D chart, so the curves themselves are the whole simulation: drag cross-link density and temperature to recompute the shear modulus G = nRT live, blend in the Mooney C2 term, and tighten the Gent finite-extensibility limit to watch stress diverge at λ_max.