A modular block, 12"x12", 16"x16", or 24"x24", painted black or neutral gray, that can be used to represent chairs, table, other furniture, etc. Usually made from 1/2" to 3/4" plywood. Another method is to stack eight 16"x16" squares of 2" thick Styrofoam, attach six sides of luaun or 1/4" plywood, and cover the entire cube in canvas duck soaked in white PVC glue.
http://schooltheatre.org/education/making/cubes
See the thread http://www.controlbooth.com/forums/scenery-props-rigging/9232-rehearsal-cubes.html .
http://schooltheatre.org/education/making/cubes
See the thread http://www.controlbooth.com/forums/scenery-props-rigging/9232-rehearsal-cubes.html .