This project aims to create algorithms and hardware that can reliably build structures in unstructured terrain. Some animals, e.g. mound building termites, are really good at this type of construction. Their skill depends on the tightly coupled interaction of construction strategy and construction material. Termites and other animals often take advantage of goopy, amorphous materials to build in irregularly shaped environments. From a robotics perspective, this approach is appealing since mechanical feedback during construction not only makes the process robust but potentially allows for much coarser control and sensing requirements of the construction mechanism. The robots I am working on use polyurethane foam as amorphous construction material. Depositions are modeled as operator applications to continuous functions, and robust strategies are designed to always reach desirable invariant sets after a finite number of depositions.