There are several articles that would suggest you may be wrong. We have to be on the constant watch for the meth addicts where I live in Appalachia Ohio. https://www.seattlepi.com/news/article/Meth-problem-hits-feed-stores-food-plants-1087177.php
LOL. Diphenhydramine (benadryl) can’t be used to synthesize Meth.
You need ephedrine or pseudoephedrine.