Abstract: An in situ molded base assembly (17) for a water ski binding (40) includes a support pad (28) composed of particles of discontinuous microbeads and a liquid phase encapsulated in an envelope to form a layer of viscous, flowable pressure-compensating material. The support pad (28) is preformed into a shape corresponding to the bottom of a foot by placement of the foot on the support pad. The base assembly also includes a soleplate (24) of thermoforming material which is in situ molded by first heating the soleplate above its thermoforming temperature, placing the soleplate over the formed support pad (28) and then standing on the heated soleplate thereby causing the soleplate to conform to the shape of the underside of the foot and the top contour of the footpad and then removing the foot after the soleplate has cooled to a temperature below its thermoforming temperature.