hello,
Normally all the object i created i can easily change the materials in Rhino but not those imported object. I’m sure it’s not a block neither a group.
what i should do to change materials with imported object?
thanks !
Hi @Yifang_ZHANG ,
Try the command RemovePerFaceColors. Post a model if that doesn’t help please.
Hi @BrianJ ! thank you for the reply. I tried it again: After i use the command RemovePerFaceColors, i need to select surfaces, polysufaces and SubDs with per face colors or materials - but i cannot select the object, even i exploded the object, it still doesn’t work
So here is the file i am working on.
thank you again for your help 
Hi @Yifang_ZHANG ,
I’m not having any issue here with your file in Rhino 7 on Mac. I opened the obj with these options…
Used the Rendering panel to restore the defaults
Made a new layer
Moved part of the model to that layer
Changed the material used for each Layer as shown
Used Rendered display mode in the view
Does that help?
Hello,
Thank you so much for the help. unforturenately, i tried exactly same thing like you did but it still not work. I will try in another computer after Chrismas😂.
i’ll keep you noted
Merry Chrismas ！