Originally Posted by ghostrider

If you're just looking for a way to mark lines on a 'custom' acrylic ruler, the easiest way is to print whatever grid/lines/pattern you want onto an Avery clear full sheet label (#18665).

All kinds of downloadable grids, etc. here (there are lots of other sites, as well). http://incompetech.com/graphpaper/ You can even print inches in one color, half inches in another and quarter inches in a third if you want. Different thicknesses of lines, too.

The labels are much thinner than template plastic and are self-adhesive so no tape is needed and the edges won't snag on things.