I just use the grouping tool do this. Here's an example with a simple object, the morphing cylinder. It has two mats: Preview (for the body) and Caps (for the ends).

In the grouping tool, I create a new group, dabody. I add the Preview mat to this. Then I assign a new mat name to it: dabody. I then create a second group, daends. I add the Caps mat to this. Then I assign a new mat to it, daends.

In the mat room, you can see all four mats now: Preview, Caps, dabody, and daends.

Back in the grouping tool, I create another group, dawholething. I add the mats daends and dabody to it. Then I click Create Prop and name it dacyl.

In the mat room, you now see three mats for this object: daends, dabody, and Preview. You can't get rid of Preview, but Caps is gone.

Let's say I want another mat around the center of the body like a ring. I create that group as daRing and select the polys I want. I assign it with a new mat name daRing. Then I select the group dawholething. I do Create Prop again and name it dacyl2 to create a third object. This has four mats: daends, dabody, daRing, and Preview.

Of course, the object can be more complex than this, but it's the same idea. I just use the grouping tool.

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Old lady hobbyist.
All visual art or fiction is "playing with dolls."