This paper introduces a method for variable-topology shape optimizatio
n of elastic structures called the perimeter method. An upper-bound co
nstraint on the perimeter of the solid part of the structure ensures a
well-posed design problem. The perimeter constraint allows the design
er to control the number of holes in the optimal design and to establi
sh their characteristic length scale. Finite element implementations g
enerate practical designs that are convergent with respect to grid ref
inement. Thus, an arbitrary level of geometric resolution can ns be ac
hieved, so single-step procedures for topology design and detailed sha
pe design are possible. The perimeter method eliminates the need for r
elaxation, thereby circumventing many of the complexities and restrict
ions of other approaches to topology design.