I want to create 4 models that will mostly move the same - the main body and hands.
However, some small details - horns, cosmetics, will differ, as well as some other elements to rig.
What are the steps I should take ?
Models each separately, Copy after main body, and model differences before rigging ?
Cosmetics are hard to imagine as anything except materials/textures. You can make as many different cosmetics as you want on the same model w/ rig as you want, there’s nothing you need to do special.
Horns, I would do as a separate decal mesh object, maybe with some modifiers as needed (like a data transfer, if I needed continuous normals with the main mesh), and copy weights from a single nearby vert on the main model.
That way, I make one main model, one horns model, one rig, and two textures. Minimum amount of work, no topo headaches.
It’s going to depend on the precise differences between the models though.