To determine value, a red plastic tool is used to see value. I also wonder about red plastic wrap if that wouldn't work,too. I have seen the red plastic wrap available for sale during the holidays, I'm not sure if it's available now. You might want to check out some quilting sites and see if they have it for sale. I don't know what the name of the plastic tool would be, but you could check out Nancy's Notions and see if they have it. I think I saw it there.