When your "roughness 3D model" is missing, it’s usually a mix-up—you’re referring to a missing roughness map (a texture for 3D models). Common causes are broken file links, unsupported formats, or unassigned material slots.
Broken links occur if the map file was moved/deleted; unsupported formats mean your software can’t read it (e.g., using .tga in a tool that needs .png); unassigned slots are forgetting to add the map to your material in the 3D program.
Try checking if the map is still in its original folder, confirming its format matches your software’s requirements, and reassigning it to the correct material slot—this fixes most issues.