A laser cutter can conveniently be used to directly cut stencils in masking tape or pretty much any tape. This tape can then be stuck to your surface, spray painted, and removed. I used this stencil to personalise the bicycle i was building for my ladyfriend.
Step 1: Lay Out the Tape on Your Laser Cutter Bed and Set the Correct Focal Distance for Your Laser Cutter.
Step 2: Design Your Stencil, I Used Corel Draw and Used a Basic Font Suitable for Stenciling.
the thing about choosing a font is choosing something where the holes in the a's and b's and d's and o's and p's don't fall out. I used the BAUHAUS font for this bike.
also make sure to convert your font to an outline so you only cut the outline.
I've attached the illustrator and post script files.