1. A method of generating a design for a device having a portion conforming to a known topology, the method comprising: electronically accessing a reference geometry representing the topology; electronically accessing a source polygonal data model, wherein the source polygonal data model comprises a plurality of source vertices; modifying position characteristics of one or more of the source vertices, wherein the source vertices are modified so that after the source polygonal data model is subdivided, vertices in the subdivided polygonal data model corresponding with the modified source vertices conform to the reference geometry; subdividing the source polygonal data model having the modified source vertices to generate the design, wherein subdividing the source polygonal data model causes vertices in the design to be positioned such that the design conforms with the reference geometry at least partly because of the modified position characteristics of the modified source vertices; and displaying a representation of the design.