I want to change old-style icons . rbz
I’ve used IconPackager myself to change icons for file types: https://www.stardock.com/products/iconpackager/
Wait, has SketchUp changed the icon for extensions to be the generic SketchUp icon?
Not that I’m aware of. But if you try to Open With and set SU to be the default app for RBZ then Windows will change the icon. (SU isn’t able to open RBZ files like that by the way.)