Systems, methods, and tools for proofing computer-aided design (CAD) objects (e.g., CAD drawings or models). The objects are implemented with CAD software and represent an apparatus. An exemplary method includes receiving a CAD object representing the apparatus, determining criteria for proofing the CAD object, determining rules, extracting items of interest from the CAD object, comparing the extracted items with the rules, and tagging the extracted items based on the comparisons. An exemplary criterion for proofing the CAD object is the type of material (e.g., a type of plastic material) for the apparatus to be manufactured in.