Duplicate material: add object name as prefix and remove .001, .002, .003, etc

Question

I need to process a bunch of Blend files that contain four objects. For 3 out of the 4 objects (doesn't matter which one is which), I need to duplicate the materials for all material slots and then rename the material to be [obj.name]+[original material name] - [.001 (or .002 or .003)]. How do I do this with python?

Answer 1

You aren't very clear in your question, so here's the answer to my understanding of it:

import bpy, re
from bpy import data as D
template = "[{}]+[{}]"
re_pattern = re.compile(r'\.\d{3}$')

mesh_obs = (o for o in D.objects if o.type == 'MESH')
for _, ob in zip(range(3), mesh_obs):
    for slot in ob.material_slots:
        mat = slot.material
        if not mat:
            continue
        new_name = template.format(ob.name, re.sub(re_pattern, '', mat.name))
        mat = mat.copy()
        mat.name = new_name
        slot.material = mat

Some changes to the previous version: Don't use continue and just allow the script to error if there's no material (sometimes getting an error is more useful than silently working incorrectly), don't use regex (for those who aren't fans of it), don't copy the materials on the 4th object, use f-strings rather than a template string:

import bpy, re
from bpy import data as D

mesh_obs = (o for o in D.objects if o.type == 'MESH')
for i, ob in zip(range(4), mesh_obs):
    for slot in ob.material_slots:
        mat = slot.material
        name_parts = ob.name.rsplit(sep='.', maxsplit=1)
        if len(name_parts) == 2 and name_parts[-1].isdigit():
            new_name = f"{name_parts[0]}.{mat.name}"
        else:
            new_name = f"{ob.name}.{mat.name}"
        if i < 3:
            mat = mat.copy()
            slot.material = mat
        mat.name = new_name