A little guide to help make custom flags for Fallout 4
I wanted to also have the included images be in the image gallery but nexus didn't take em, sorry about that.

Here is the directions text file included within download:

Easy Custom Flag Textures Tutorial
    -The Purple Marine
    
In order to use these resources you are going to require an image editing program. Not MSPaint, but something a little more, comprehensive.
I personally recommend GIMP because it is multiplatform and free, but you are probably able to do similar things in other programs (Keep in mind the process will probably differ slightly from this guide if you are using another program).

1. Load the BlankFlagUnripped.png file into your program
2. Create a new layer and set it to "overlay", make sure this layer is above the original one
3. Create your design on this layer(Keep in mind, the top half of the image is going to be used for certain flag models, while the bottom half will be used on others)
    -I recommend creating your design once and then just copying it again on the bottom side of the image
4. When it's done, you can flatten the layers and if you're happy export it as a DDS file, and make sure the compression is set to "BC1 / DXT1"

If you'd like to have your flag have rips on it, then you should

5. Go to Colors > Components > Decompose and select RGB
6. Load the TatteredFlagAlpha.png file
7. Go to the decomposed version of your flag, and then go to Colors > Components > Compose and select RGBA
8. Leave all the boxes the same, but in the Alpha selection select TatteredFlagAlpha.png
9. If you want to, you can mess around with how damaged the flag is by going to Layer > Transparency > Threshold Alpha
10. When you're done, export the same as before

Congrats on the flag!

Credit goes to Bethesda for Fallout 4