Wax carving is the shaping of wax using tools usually associated with machining: rotary tools, saws, files and burins or gravers. Actual knives can be used and most certainly are, but the hardness of the material is such that they are not the ideal tool, generally.
To carve wax, the proper size and shape of block or tube is chosen, in the preferred hardness, and cut to a rough size, as needed. Then the design is generally drawn or laid out on that, and saws, files or machine tools are used to work the wax into a finished product. The wax is easily taken to a fine finish in the end using a bit of nylon stocking or steel wool. After the wax product is finished, it may be molded or used in the lost wax casting process to create a final cast product.