Things You'll Need
Instructions
Open GCFScape, click "File" and select "Open" to go to the "Steamapps folder," where you will find the file "materials.gcf."
Select the "materials.gcf" file and click "Open" to view its content files.
Browse through the "Models" folder to find a skin that you want to edit and personalize. Select the skin file and right click on it. Select "Extract to" to place it in a separate location.
Open the skin with photo editing software. Change the color scheme, outfit, size, shape and details of the skin using the color and cut options available in the software. Once complete, click "File" and select "Save" to keep the changes.
Open the "GMod" installation directory, which is located on the main hard drive in the "Program Files." Place the new skin file in the "Models" folder.
Close the folder and load "GMod" to test your personalized skin.