Save your current 512 x 512 graffiti (Drips) version as a .png file
Creating Directories (One-time)
Navigate to <Steam Install Directory>\steamapps\common\GarrysMod\garrysmod
Create a folder called "materials" if it does not exist already
Within the "materials" folder create another folder called "warzone_itemtest" if it doesn't exist already.
Finally, create a folder if it does not exist called "graffiti"
Importing to Workbench
Copy your newly saved Graffiti .png file to <Steam Install Directory>\steamapps\common\GarrysMod\garrysmod\materials\warzone_itemtest\graffiti
Open Garry's Mod and connect to the Skin Testing Environment https://warzone.gg/serverinfo/44
Put "warzone_item_tools " in console to open Workbench
Go to File > New
Enter the project details and set the type to "Graffiti"
Depending on how you designed your graffiti, you will have to select the style. At the top select Graffiti Style and then click on Monochrome or Full Color.
Next click Edit > Set Material and click on warzone_itemtest/graffiti on the folder explorer.
You should be able to see a list of files including the one you have copied over.
Select the material from the file browser and then click "Selected Material"
Your newly created Graffiti will now appear on the wall
If your graffiti style is "Full Color" make sure you are happy with how it looks in-game and make any changes needed.
If your graffiti style is "Monochrome" you can go ahead and preview your graffiti with the inbuilt colors and create your own pattern floats.
At any time you can Click Tools > Reload Material to live reload the material cache,.