The problem with a beaker, apart from the crafting itself, is you won't know you did your work well until you use it multiple times and test if the equal values increments you marked on it are correct.
Imagine mixing explosives powders, potions or poisons but messing up the right quantities because your beaker is not measuring correctly.
Especially with explosive powders you could end up crafting a dud or even having the misture blow up in your face because the proportions for the recipe are not translated right in the beaker.