Although active diapirs must deform the overburdens they pierce, the shape of passive (downbuilt or syndepositional) diapirs is formed or molded by their overburdens. Molding of salt diapirs is simplified here to profiles of diapirs entirely downbuilt in effectively rigid overburden. The dips of salt-sediment contacts are shaped by the interaction of two processes: local net accumulation of overburden (A = deposition minus compaction) at rate and the net increase in relief of salt structures (R = salt rise minus dissolution) at rate . Steady kinematic molding ratios, /, forward model realistic dips of molded salt contacts, a, at particular depths using / or / = tan a/2. Rising or falling ratios of incremental molding forward model complete diapir profiles. Conversely, molding histories can be read by backstripping profiles of downbuilt diapirs. Salt diapirs are downbuilt in a field of downbuilding (100 > / > 0.01), that is bounded by burial and extrusion. Within this range, aggradation faster than salt can rise (/ 1) molds flaring (widening-upward) salt contacts. Below this range (where / ~100, salt emerges like a fountain and extrudes sheets of allochthonous salt. Extruded salt is recycled back into the ocean by dissolution at the surface or after burial and reactivation in another cycle.