I have this .stl that I downloaded and I need to create a solid of this 3D. However, if I click "Make solid", it doesn't work.
How can I do? I think the problem is the black layer but I don't know how to resolve.
Before make solid:
After make solid:
I need to make solid and the black layer is deleted when I do it.
https://drive.google.com/file/d/1g-YaF1k_X5FU1Y-SgWiGCXC4k_nADohk/view?usp=sharing
PS: The other object are different item, so if they are there or not is the same