Accurate, consistent, and continuous thermodynamic and transport properties are essential to the analysis and design of energy devices of all sorts, from power generation to product manufacturing. Articles and papers abound covering various aspects of this important field. Often these are esoteric and omit details on how the process is accomplished. The end result of property research may be inaccessible to practitioners, who would use the information to create and manage the machines of industry. This text is a step-by-step manual on why and how to develop and implement functions for thermodynamic and transport properties from raw data to Excel(R) Add-Ins.