These are the cheapest I have found. I am going to stop at Harbor Freight and purchase a couple to see if this would work. There was also a suggestion that Menards has them for under $3 as well. While I can find them online at Harbor Freight, I can't find the reasonably priced ones at Menards.

I am willing to try most anything. I am having so much trouble with getting the ruler ( which is plastic and very slippery. ) to stay put. The ruler brand I purchased was : EZ Ruler. The markings on the ruler are black ....