Custom-made 12"x18" stencil in blue (for solid surfaces) or purple (for textiles/fabrics).
 
Blue is pressure sensitive and has a lighter adhesive.  Purple has a stronger adhesive, but lets through a little less paint/ink.  The type of stencil you use is really a personal preference.  Some like only the purple and others like only blue, while others use both.
 
Please note there is a $5 designing fee added to each custom stencils.