This article discusses an object-oriented approach to industrial software development using Mathematica. We present the package Elements for structured representation of physical, engineering, and mathematical objects. This package introduces object-oriented paradigms into Mathematica and is used to develop a modeling environment built on a knowledge base where class and object properties and relations are maintained in a consistent, transparent, and extensible way. We show how this tool can be applied to design models parametrized by structured objects instead of just simple values.