Abstract: A prospective user of a supportive seating system is initially measured in an approximately correct seating posture to determine which one of respective pluralities of modular preformed seat and back bases can best accommodate him. Elements of firm resilient, sculptable material are selected from precut modularly sized and shaped pluralities of the same, for assembly and attachment to the seat and back bases to create approximate support topologies. The user is seated in the support system and, based on his responses, the support topology is sculpted to custom-fit his specific needs. A temporary covering is applied to the seat and back modules. After a trail period, the quality of the custom-fit is reviewed for further sculpting as needed, and a permanent cover is then attached to each module.