A method and apparatus for manufacturing a bat having an exterior and a hollow interior. In one aspect, an input graph is validated against a model template graph. The material can be the base layer of gallium arsenide-based heterojunction bipolar transistors and can be lattice-matched to gallium arsenide emitter andor collector layers by controlling concentrations of indium and nitrogen in the base layer. Each switching circuit is connected to the input in parallel with each other switching circuit. Traction fluid of various sorts may be used in the variators, not just high performance synthetics or application specific lubricants.