This document discusses claytronics, which is a concept that combines nanoscale robotics and computer science to create individual nanometre-scale computers called catoms that can interact to form 3D objects. Catoms are envisioned as self-contained units that can move and adhere to form shapes under software control. The document outlines challenges in designing catoms that can move and connect in 3 dimensions without moving parts. It also discusses software languages like MELD and LDP being developed to program large ensembles of catoms. Potential applications mentioned include new modes of communication that allow physically interacting with remote objects.