I am Mechanical Engineer. As a freelancer, I dedicate myself to developing parametric families in Revit, based on the technical information of product manufacturers. My client sends me the all available technical information about the product. I send back a proposal where I describe the features, functions, and prices of the model, always based in a 350 Level of Development (LOD) Specification. My client chooses the features that want in its model. I begin to design the model and my client pay me when I sent the zip file that contents the rfa files.