  We present design and implementation of a chain of particles that can be
programmed to fold the chain into a given curve. The particles guide an
external force to fold, therefore the particles are simple and amenable for
miniaturization. A chain can consist of a large number of such particles. Using
multiple of these chains, a shape-shifting display can be constructed that
folds its initially flat surface to approximate a given 3D shape that can be
touched and modified by users, for example, enabling architects to
interactively view, touch, and modify a 3D model of a building.
