Roblox Studio Join Surfaces. Last fall, we removed hinge and motor surfaces, and at that point, the surface tool in the model tab became solely a visual change. According to the wiki, unjoinable “makes two surfaces unable to join no matter what” and weld will “join to any surface except for unjoinable.”.
If playback doesn't begin shortly, try restarting your device. Why aren't they supported anymore? Glue was a type of surface that could hold together two parts.