Luis Leguia couldn’t find a cello he liked. “So he invented one himself using an unlikely material — carbon fiber. And now he designs, manufactures, and sells carbon fiber cellos, violins, and violas through Luis and Clark Carbon Fiber Instruments, a company that he started five years ago and runs out of his home. Carbon fiber, strong but flexible, is strands of carbon tightly woven and set in resin. He has sold 100 cellos, 12 violins, and 20 violas.”