Mylar thickness is critical for different application methods. A "mil" is 1/1000th of an inch.
: Sells Grafix Stencil Film, a polyester film (similar to Mylar) often available in a light blue tint for better visibility during hand-cutting. where to buy mylar for stencils
: A good source for bulk packs of pre-cut sheets, such as 10-piece or 25-piece sets of 7.5 mil or 10 mil material. Comparison of Stencil Mylar Options where to buy mylar for stencils
Mylar for stencils is widely available from specialty stencil manufacturers and major craft retailers in various formats, including individual sheets and bulk rolls. The best place to buy depends on your project's scale and whether you need specific thicknesses (measured in "mils"). Recommended Retailers where to buy mylar for stencils