In large mixing bowl, mix together the plaster of paris and water (two parts plaster to one part water). Stir until the mixture is smooth.
Give each child a handful of plaster. Ask each child to mold the plaster into a mound, about 3" in diameter.
Children will decorate the plaster mounds by pressing a variety of nuts, bolts, nails, and screws into the surfaces.
Set the children's paperweights on old newspapers and let dry for two or three days.
When the paper weights have dried, spray-paint them silver. Let dry.
To make a protective covering for the bottom of each paperweight, ask each child to trace the paperweight onto a scrap of felt, using chalk. Assist each child in cutting out the felt shape and trimming its edges another 1/4 ". The felt shape will then be glued onto the bottom of the paperweight.