I use photoshop to make the flags for the game. Here are the files if you have a copy of photoshop and want to make a new flag that matches the existing ones:
The zip contains 2 files:
1414.psd. This is the ‘displacement’ file.
That is the multi-layered photoshop file that is used to make the flag. Basically get a 1024x768 flag image and paste it as a new layer into the main psd. set its blending options to soft light, and delete the german layer (or hide it). Then go to filter : distort : displace and choose 10 for both scales. When it prompts you for a displacement file, select 1414.psd. Then save the whole composite image down as a bitmap, and enlarge the canvas so it is 1024 X 1024 with the flag at the top bit.
That should be it!