I've done a over one hundred boards with a Kapton stencil without any problems (0603 size parts) and 50 boards with a stencil cut out of vellum paper (a plasticized paper available at craft stores, red cuts very well with 405nm lasers) by my home-made laser cutter head for a desktop CNC mill. I've never worn one out or ripped one... YMMV. I'd probably go with stainless steel for something with tiny BGA's, but have done chip-scale IC packages with paper stencils. It's only recently that small stainless steel stencils have become easily available and cheap. ----------------------- Laser cut Kapton are fine for a few boards - up to 5 or so. You start seeing the effects of use after six or eight and steel is clearly a value. . I use them for most protos.