Use an art program, photoshop, Paint.net or whatever. Using the template, search for what you want online that will fit the template box. Search using a PNG file. Use your the selected image as a mask layer and over lay the location template. Make sure to remove the background on the mask layer. You can literally add anything. A weapon, a bottle of alcohol, a laser pointer, a sexual aid...etc. just position the size and angle to fit the mask. Add color on a separate image calling it the color mask. You are only limited by your imagination. Once you create the image, insuring it fits the position template, create the new asset in game. Adjust the image as needed.
