I love the Advance Wars series and I decided to make in 3D almost all the terrains from Advance Wars DS and the portal tile from Advance Wars by Web. You can download this either at my itch.io (Blender) or Sketcfhab (FBX) for free.
I'm also in the middle of a Kickstarter campaign to promote my free assets as well.
In my Kickstarter I'll do units invented by backer but they'll work with all my free assets.
Disclaimer:
I don't own any of this material, everything belongs to Nintendo and Intelligent Systems.
All my free assets of the terrain tiles from Advance Wars.
Early video of the terrain tiles.
Recon attack! Example of what you can do with my free asset pack (made in Blender).