A cook

A person who "cooks" methamphetamine either powdered or crystal, some folks do it to get high themselves because it's not rocket science you can literally do it in your kitchen sink hence "cooking" with chemicals you can find in your local shop. There are different ways- the "shake n bake" and the red phosphorus method. Now there are some Breaking Bad type of cooking but you're not gonna see an average junkie doing that you gotta have the specific flasks and not only that but the chemicals themselves plus gotta have some chemistry knowledge. And don't fuck around with meth you don't want that horrible stuff in your life.