In all Seriousness WL does sell a cap that makes a cross, so that You might be able to use that if You can ignore the other line. I think You can get optics to produce a Line from Edmund Optics.
Any cylinder of glass (or plastic) will generate a laser line from a dot. People use wine-glass stems for a non-professional solution.
You could get a (professional) line-generating lens for $3.00 at Aixiz: