Categories to help selecting a starting point
A flat list of categories is highly recommended - then filters, hierarchies, features to narrow to a set of candidates.
The Categories may also be encoded, to help with assigning variables and model names. For example, the first few categories "singlePLA", "printed-COTS", "printedPLA-printedABS", "printedPLA-customALUMINUM" can also be used in wrapping existing modules / models into more descriptive names.
The complexity comes from observations explained in CAD Data Considerations and elsewhere. Parametric design is not always going to help with every requirements, but categories may help separating nearly identical models when it makes sense. Example of this is when the model is printed with a variety materials, nozzle sizes, scale and set of features.
What is considered "base model category" is discussed in this thread.