So i have designed a mechanical linkage system that allows a tracer to trace over a semi circle object. I am now at the point of deciding what materials i should use for the links in the system. The system isn't a massive structure. The semi circle object that the system has to trace over is 500mm in diameter. I would also have to account for the weight of the servo motors involved, which roughly should be no more then 500grams. What would be the most suitable materials to use?