The deformation elasticity behaviour of re-entrant auxetic structures with a bow-tie shape, made of silicone elastomer, is systematically analysed for size accommodation and shape conformity, and compared with traditional polyurethane foam and spacer fabric used in bra pads. The results indicate that the auxetic structures exhibit desirable mechanical properties, including superior elasticity and stable deformation under tensile loading. Additionally, these structures facilitate 3D shape conformity to breast shapes, thereby improving overall bra fit.