Someone has perfected a (meth)amphetamine lab design that uses multiple productions lines in parallel. No glass is used. 50L stainless steel beer barrels are used as reaction vessels and somewhere an experienced welder is producing huge still-heads & Liebig-type condensers Heating it undertaken using bottled propane (so no unexpectedly large energy bills) & the freebase (meth)amphetamine is converted to it's phosphate salt.
The phosphate salt was a Russian (or possibly Soviet) invention. It was a Russian-language paper that first details it and proves to be MUCH simpler than producing the sulfate and only slightly more complex than making the hydrochloride - BUT it's suitable for both amphetamine and methamphetamine.
Almost all of the BMK is produced in Russia (where it is legal) in commercial reactors. A specific side-product identifies it. But people have produced MANY addition complexes so that a white solid rather than a liquid is transported - and much harder to divert.
The ONLY difference is that formamide (also a common solvent) is used to make amphetamine or is made from ammonia & formic acid (actually it makes ammonium formate but heat causes dehydration).N-methyl formamide has to be made from methyl amine and formic acid. In fact, N-methyl ammonium formate likewise loses water when heated producing the N-methyl formamide.
It's a VERY simple way to make (meth)amphetamine. Not the simplest nor cleanest nor the highest yielding BUT it can be scaled. The only limits are how efficiently the mixture can be heated and how excess heat can be removed.
I've seen one lab in Poland that had 6 of these beer-barrel type reaction setups all in the cellar of a closed brewery. They just scoop of the freebase product (in normal kitchen plastic vessels) and add phosphoric acid. In 1 8 hour shift they could produce about 180Kg of amphetamine or methamphetamine.
What is important to know is that although supposedly similar, some nations prefer amphetamines, others prefer methamphetamine. It may be cultural as to how people use their stimulant of choice but the production costs are the same BUT meth is worth more.... so I'm sure attempts were made to introduce meth into nations that prefer speed.... but it didn't work, or at least speed it considered a soft-drug, meth a hard drug (in social circles, not in law).