dies 11 12 includes a rectangular block of ceramic material 23 reinforced by a set of fiberglass rods 20 and a set of support plates 17 the support plates are preferably a set of phenolic boards arranged in the shape of a rectangular box framing each ceramic block 23 the phenolic boards 17 serve as containment walls during casting of the ceramic blocks 23 and also provide reinforcement during the subsequent induction heating process phenolic boards are typically composite plates including linen or other fibers suffused with an epoxy resin as shown in fig1 the fiberglass rods 20 extend longitudinally in a first array and transversely in a second array so as to form a grid through each ceramic material block 23 the ends of the fiberglass rods are threaded and extend through respective opposing ones of the phenolic boards 17 the grid is embedded into the ceramic block 23 by extending the fiberglass rods 20 through the phenolic boards 17 before casting the ceramic material block 23 after the block of ceramic material is cast a set of nuts 21 are placed on the threaded ends of the fiberglass rods and are tightened so as apply a compressive load on the phenolic boards 17 the compressive load on the boards.