I’ve seen this done before and would like to do it but I’m not sure HOW to go about doing it. The model in question was a human figure (although this should work for any model) composed of many objects. Smaller pieces were parented to larger objects, or sets of objects - a finger to a hand and a hand to an arm for example - and were each selectable individually and as groups. Being a noob I am rather ignorant of the vocabulary and of the techniques one would use to bind objects together like this effectively but I’m intrigued and reason that modeling a modular setup would be a lot easier than a model that had to be redone for every picture.
It sounds like you want to animate this figure. For that you will want to add an armature, and rig it. This can be accomplished in various ways, but for multiple pieces, you’ll want to parent the objects directly to the bones. The way to do this ( after making your armature ) , is to select your armature, then press ctrl tab to go into pose mode, then…say you want to link the forearm to the forearm bone. select the forearm, then, shift Rclick the forearm bone to select it also, and press ctrl P to parent.
There’s also the option to use the Armature modifier in each object and point the modifier to the skeleton. Then the Vertex Groups will do the rest.