You can create your own materials (stainless steel, steel by editing the materials) and specify in the drawing which materials are associated with the different parts of the room.
Or you can also associate a material by volume in the build tree by right-clicking on a body and associate a material.
Hello
What do you mean by assembly?
Hello Pascal,
I agree with Jules, and I will add that it would be better to change your part to a mechanically welded part, so you can use his nomenclature of welded parts for its drawing.
That's it, it's the best solution to your problem.
@+.
AR.
Jules B's answer is the best answer. I'll just add one thing, this solution works as long as your part file has several sizes.
Let me explain, if you make for example several extrusions and you leave the "merge result" box checked, it will give you only one body in the "volume size" file of your Featuremanager.
On the other hand, if you uncheck the box when performing your different functions, then there will appear several bodies and at that moment you will be able to assign a different material to each volume body as explained in the Post above by Jules B.
Kind regards