  We present progress on the problem of reconfiguring a 2D arrangement of
building material by a cooperative group of robots. These robots must avoid
collisions, deadlocks, and are subjected to the constraint of maintaining
connectivity of the structure. We develop two reconfiguration methods, one
based on spatio-temporal planning, and one based on target swapping, to
increase building efficiency. The first method can significantly reduce
planning times compared to other multi-robot planners. The second method helps
to reduce the amount of time robots spend waiting for paths to be cleared, and
the overall distance traveled by the robots.
