Making TMA-2 isn't all that complicated, it's just that people rarely do it because it is illegal in a lot of jurisdictions, and people who operate on an illegal market tend to prefer substances that are highly potent and thus easier to smuggle. Sure, TMA-2 is roughly ten times as potent as mescaline (with typical doses between 25 and 50 mg), but then again DOM is active between 2.5 and 5 mg, and produces relatively similar effects.
Still, I could see why in a less "legally-enforced" environment like Mexico somebody would get away with making large amounts of actual TMA-2 in order to achieve a more "authentic" mescaline-like experience. I've found a report on WEDINOS from 2014 where somebody submitted a sample sold to them as TMA-2 which turned out to be legit. About a year ago, a Swedish vendor also sold a batch of TMA-6, which supposedly produces pretty much the same effects as TMA-2 at similar dosage levels, but it also has the advantage of being not quite as illegal in many jurisdictions.
Anyway... as I said, a typical dose of TMA-2 is 25 mg, which would be wayyy too much to fit on a blotter tab, but I could see enough of it fitting into a geltab/windowpane to be viable.