Also called marble dust, chalk and calcium carbonate, this powder is truly a general purpose filler. It can be used in resins, glues, paints and even rubber. Make your own gesso with a little rabbit skin glue and white pigment; add it to polyester resin with a little pigment and you have a great general purpose casting resin; mix it with some acrylic emulsion along with a little thickener and you have modeling paste. Again, the possibilities are endless. And it's cheap too!