Over the years Walmarts had offered a spray paint camo kit, made by Krylon, in the Sporting Goods section. It came with 4 cans of black, browns and greens and a few stencils. I did my squirrel gun in it a few years ago and it came out pretty good. They are flat, earth tone colors.
I also cut a few more stencils myself from small leaves I picked up in the areas where I hunt squirrels.
I haven't seen the kits this year but I haven't really looked for them either. More Stencil materials can be found in the Arts and Crafts section and cans of flat spray paint in the Paint Dept in Walmarts.
So far it has held up good under hunting conditions. Even if it did get scuffed, it's easy enough to get the can and stencil out and go over it. The squirrels won't know the difference.