Hoe to make custom camos??

what's up guys

i've been looking for how to make custom camos, but all i've found is how to make camos for specific weapons.
All the tutorials teach how to customize weapon colors instead of the camos.

i wil be gratefull if you guys teach me how to make custom camos.. i've seen a lot of threads of people sharing their custom camos but no one tells how to do that and again i will be very gratefull if you guied me doing this.

thnks for your time guys