I use them for everything from mixing to scooping. This expensive tool is used to balance the sweetness of sorbet. It measures the total sugar content of a sorbet base. If you plan to make sorbet often, a refractometer is a good investment because it provides an easy and accurate measurement. They allow the food to cook evenly and help keep milk products from burning.
Pastry is a relatively exact science and the volume measure of cups is very inaccurate.
I use an Edlund digital scale, DS-10, that weighs measures from 0.1 ounce to 10 pounds, or 2 to 5000 grams. Less expensive scales are widely available. If you are going to use dry-cup measures, keep in mind that during testing I used the cup to scoop up the ingredient and then leveled the top with an offset spatula. I did not pack it or tap it down. Whenever an ingredient is sifted, I always weigh it before I sift it.