The complex interactions of natural swarms, for example formed by some social insects, are difficult to comprehend. Considering tasks such as nestbuilding, the necessary underlying communication presumably happens indirectly by changing and reacting on the environment. This paper presents an overal approach to interactively evolve rule-based swarms that create three-dimensional structures in continuous space. The approach comprises the design of the swarm agent, details about the breeding process and first results. A swarm is determined by a set of flocking parameters and a set of instructional rules that allow the agents to change their local structural environment. The center or focus of the swarm’s endeavour may be shifted either on a swarm agent or on a fixed point in space. The alteration of the supplied 3D structure during the course of evolution enables an external supervisor to interactively guide the development of a swarm.