Instructions
Download and install GcfScape (see Resources). Open GcfScape and click "File" and "Open," then browse to your program files for Steam. Under C:\program files\steam\steamapps, double-click on the file "share.gcf" for "Counter Strike." Wait for a list of files and textures to load for "Counter Strike."
Go to "ccstrike\materials\models\weapons" and choose the skin you want to alter, such as for a "c4" or "pist_elite." Find the skin you want to edit and click the folder, then click on "Extract." The files extract to a folder on your desktop.
Download and install VTFEditor (see Resources). This program lets you convert game files into graphic file formats that you edit in image editing programs. Once installed, open VTFEditor, click "File" and select "Open." Find the extracted file of your skin and double-click to load in VTFEditor. Click "File" and select "Export." Choose .JPEG or .PNG as your file format. Your new file saves to your Desktop.
Edit the image in an image editing program such as Adobe Photoshop, GIMP or Corel PaintShop Pro. Find images of other guns and texture the image as you like. Add in contrast with blending modes such as "Darken" and "Multiply." Change the "Brightness/Contrast" level of the image. Add in effects such as motion blurring and distortion. If you have trouble using the tools of the program, find tutorials about making gun textures to direct you to a combination of effects.
Save the new image with the exact same name as a weapon within the game. Some weapons include "rif_ak47," "rif_aug" or "mach_m249para."
Open VTFEditor again and click "File." Select "Import." Find the new picture that you edited for the game. Double-click to open. Click "File" and "Save As." Save to the folder that you exported from GcfScape to your Desktop. The file must have the name of your gun and the same name of the original file you exported.
Open your program files Steam folder. Go to your "steamapps" folder. Click on your account name, then click "cstrike\materials\models." Create a folder called weapons. Copy the file from your Desktop and paste into the weapons folder.
Launch "Counter Strike" as normal and select your new weapon.