The applications of technology in instrument design contribute to the resulting sound on many levels, particularly in the context of new evolutions representing the traditional instruments of our culture. Materials technology is seldom given consideration in the description of Western string instruments, but our choices of woods, metals and synthetics can dramatically alter the sound without altering the substance of instrumental performance. In the design of modified string instruments which mimic features of natural acoustic predecessors, new technology is applied on many levels. A taxonomy is proposed for the past, present and future of instrument design. Due consideration is given to the music which results from the new sound world, especially that involving interactive electronic processing. The advantages and disadvantages of directions in instrument design for the future are evaluated within the proposed schema. Some extended techniques on the cello are proposed to be further extended with electronics, and audio examples and descriptions are provided. A model for future collaborations between composer, performer and engineer is proposed.