@Grintch All the related graphics are inside the “assets” folder of your TripleA installation.
Additionally there are or may be graphics inside the map.zip-files of the map you are interested in.
In case there aren’t any graphics in the map.zip-files, those in the assets folder of TripleA are used.
So you usually would change the unit-design in the map folder or add your own units there.
Those files are png-files, so you can customize them with any image manipulation software.
For deeper information I would recommend that you open a thread here:
https://forums.triplea-game.org/category/28/map-making
There are active map makers who might help you.
Good luck :slightly_smiling_face: