This paper describes a systematic approach to specification and compilation of different physical modeling schemes particularly for sound synthesis studies. First we formulate theoretically a unified way of constructing physical interaction models which include elements that use both wave variables and Kirchhoff variables. These elements can be applied to build 1D and multidimensional structures as well as lumped element models. In addition, typical signal processing algorithms are supported. A software environment (Block Compiler) has been developed, allowing for high-level object-based specification of physical models and their compilation to efficient code for execution.