Are you talking about measuring a mass of solid NaOH by volume? If so, I'm afraid you're out of luck. Different batches of lye might have wildly varying densities- for instance, I have both powdered and pelleted NaOH, and though I've not checked, I'm confident that they will not be of the same density. There are just too many variables to consider. I would advise either that you invest in a scale, or that you buy some pH papers. The latter will be cheaper, and you will be able to perform a perfectly effective extraction by just adding lye until the pH is 14. You could also make a saturated aqueous solution of NaOH, find out the concentration of a saturated solution at that temperature, and then calculate the mass per unit of volume from that. Hope this helps, good luck!