Dust3D
Dust3D is a cross-platform open-source 3D modeling software
...Dust3D is a cross-platform open-source modeling software. It helps you create a 3D watertight model in seconds. Use it to speed up your character modeling in game making, 3D printing, and so on. Yes, it's free. And it's cross-Platform, no matter you are on Windows, Linux, or MacOS, the same experience you'll get. Give it a try. With Dust3D, you'll see yourself finish a game asset in a blink! Dust3D also supports export your model as FBX and glTF format, so that you can then import the files into software like Unreal Engine, Unity, and Godot for further development.