Tutorial(s) for creating complimentary pieces?

I’m not sure what the correct terminology is but….. Most of the scenario’s I have for using a 3d scan, is to create complimentary pieces to the target of the scan. For instance I scan a car part with 4 exposed bolts, and I want to create a cap that bolts down over that part, are there any tutorials specifically aimed at a scenario where I want to create an object that fits over those bolts. Basically, I’ve scanned a shape, and need to create the reverse of that scan.

Additionally, from a terminology perspective, what term should I be searching for? I generally need to create things that fit into a void, or slide over bolts, etc etc.

Thanks in advance!