If when importing the model to roblox studio. your textures are missing like in this picture. but in blender everything works. you need to recalculate normals
Turn on Backface Culling
when you’ve done everything - select the mesh -enter to edit mode - select all faces - Shift+N to recalculate normals
Then click on recalculate normals and click “Inside”
The Outside faces really help out when making awesome effects on objects like unique outlines that work better than Highlights as they’re not buggy whatsoever.