Step 1: Welcome
By printing your stencils via a 3d printing service instead of cutting them out laboriously like some dolt, you can have razor sharp edges and a wide range of designs. Plus the stencils you produce will be strong, sturdy and dam impressive.
What the spray can stencil attachment will allow is for you to take your artwork to a whole new level, via 3d printing and a free modeling program called blender.
Step 2: Doubletake
I've attached a model of a simple spray can if you would like to follow along.
It will allow you to make your own design that you can get printed if you'd like, because the concept is fairly simple.
Step 3: Steps
Basically what you need to do is to create a frame that can support the stencil.
You can either copy what I did, or make it your own.
Step 4: The Stencil
I have chosen this an image of Gir as mine.
You can do one of two things.
Either you can put it as a background image, or apply it as a texture, (sizing is required). Either way should work fine, because you should be working with a singular plane that's highly subdivided, so you can easily extrude it to the desired thickness later, which happens in this case to be .1cm.
You need to make the areas where the paint will pass void of material, this can be accomplished by moving vertices and deleting edges. If you have any questions feel free to ask.