Preparing the mesh for Unity

Prerequisites
Setting up Unity
Modeling the mesh in Blender
Texturing the mesh in Substance 3D Painter

1. In Blender, make sure that the origin of the object is where its center of mass would be.
2. Move the object along the vertical axis so that it rests at 0;0.
3. Rhe object must be at scale 1 (otherwise the shape will not be preserved in Unity). If not: Ctrl+A > Apply Scale.
4. You might as well apply rotation while you're at it.
5. Right click on the object name > Select hierarchy.
6. Click on File > Export > FBX. Give a specific name to the file (eg: my_mod_engine.fbx).
7. Check “Selected objects”.
8. Uncheck “Precalculate animation” (“Bake animation”).
9. Click on “Export”.