A system for movement in a body and performing a function on the body. The system comprises a polymer body portion, an electronic unit carried by the polymer body portion, a circuit in the polymer body portion operatively connected to the electronic unit, pieces in the polymer body portion, and a system for controlling movement of the polymer body portion utilizing magnetic forces controlling movement of the pieces. The system utilizes magnetic guidance to control movement of a polymer body portion.
 The United States Government has rights in this invention pursuant to Contract No. W-7405-ENG-48 between the United States Department of Energy and the University of California for the operation of Lawrence Livermore National Laboratory.