Select Meshobjects , end with that one that you want all the rest to apply same material as the last one. press CTRL - L chose Materials
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Yes I know, you can also set one Material for the hole Layer in Cycles.
But I wanne be sure that Cycles really only loads the “Layer-Material” to the GPU-Memory.
I’m analysing how mutch Memory the Textures of my Scene in the GPU-Memory needs.
You’ll need a script to do this I think. If you’re still interested PM me and I’ll write you one (should only be about 4 lines) if you’re not sure how to do this.