Draw your design on the Styrofoam block with the marker. You do not want to start carving unless you have a design.
Chop off a large piece of the Styrofoam with the long-bladed knife. This helps you make an accurate cut later.
Carve out the design with a short-bladed knife. Go slow with the knife. With slow movements, the design will look much better than it would if you moved fast.
Wipe away any small pieces of Styrofoam stuck to the sides of the block.
Paint the Styrofoam with acrylic paints, as acrylic paints do not melt Styrofoam.
Vacuum the floor to clean all of the small chunks of Styrofoam off the floor.