This paper presents two new musical robot systems and an accompanying driver electronics array. These systems are designed to allow for modular extensibility and ease of use with different instrument systems. The first system discussed is MalletOTon, a mechatronic mallet instrument player that may be re-configured to play a number of different instruments. Secondly, the Modulet mechatronic noisemakers are presented. These instruments are discrete modules that may be installed throughout a space in a wide variety of configurations. In addition to presenting the aforementioned new instruments, the Novalis system is shown. Novalis is an open-ended driver system for mechatronic instruments, designed to afford rapid deployment and modularity. Where prior mechatronic instruments are often purpose-built, the robots and robot electronics presented in this paper may be re-deployed in a wide-ranging, diverse manner. Taken as a whole, the design practices discussed in this paper go toward establishing a paradigm of modular and extensible mechatronic instrument development.