A pumice sponge is a block of handheld sized pumice that is most often used to exfoliate dry skin, particularly from the heels and feet. Raw pumice is formed when lava explodes from a volcano and reacts with water. The simultaneous cooling and depressurizing of the lava and water mixture gives pumice its unique porous texture. Raw pumice is inexpensive and easily carved, so buying a large piece of pumice and shaping it into smaller sizes is cost-effective for commercial or personal uses.
Decide the size and shape you wish the pumice sponge to be. Make sure the design is smaller than the raw pumice. Mark an outline of the shape with tape or permanent marker on the raw stone.
Carve your marked design with a metal spoon and dampen the pumice with water if it starts to crumble.
Drill a hole approximately 1/2 inch wide into part of the shaped pumice sponge if you wish to place a rope for hanging at one end. Feed the rope or string through the hole and tie the ends in an overhand knot.