For anyone who has had chemistry, knock the oxygen off the ephedrine molecule and you get methamphetamine. Hmmm--- iodine and--- of course! But there are other ways of combining carbon-hydrogen molecules with nitrogen. All you stop by the restrictions are the simplest-minded kitchen sink type producers. There are many possibilities for designing your own drugs if you are so inclined.
The "war on drugs" as now waged will be never-ending and never successful until the profit incentive is removed. That possibility in the States seems dim.