According to the available information, in Mexico, meth is produced starting from benzyl cyanide (or benzyl chloride), via APAAN, BMK and formic acid/methylamine. The resulting racemic meth is then resolved, using, very likely, tartaric acid or a derivative thereof (e. g. dibenzoyl tartaric acid), producing the desired (+) meth (i. e. dextrometh). Finally, the free base is treated with HCl to get the final product, i.e. “ice”. The (-) meth is discarded, as it is inactive. The resulting ice still has a small amount of (-) meth (few per cents, as detected by chiral HPLC), but that does not affect the potency. Apparently, a profitable and efficient procedure, despite that one half (- meth or levometh) is discarded.
It seems that they do not use any chiral precursor (e.g. +ephedrine or +pseudoephedrine), unlike some other manufacturers.
So, most likely, Mexican ice is a genuine, “made in Mexico” product.
But, in producing fentanyl, it seems that Mexico is much less self-sufficient, supposedly depending on some imported precursors. (Still, it is cheap). Much more so in the case of 3-Me f. and carfent. (Actually, these are hardly produced there, although could be highly profitable).
They might be interested in purchasing industrial, know-how procedures, to get fully self-sufficient.