Space captain:
I peeled the cactus, cut it into spears (in the troughs, cut towards center of cactus, you get spears), took the white matter out, leaving the peel and the dark green flesh. took the peels off, blendered the shit out of the dark green, boiled it for ~3 hours, added pure lime juice until pH was ~3, cooled mixture, washed with petrol ether, then filtered. You end up with a limey-tea that tastes like neo citron, and has the consistency of a light hot chocolate. Used about 18 inches of 3 inch diameter cactus. That's about 3/4 of the way to a heroic dose.
Another method is to get to the boiling step, boil, add HCl until pH is ~2, wash with petrol ether, add NaOH until pH is ~11, wash with petrol ether, add a bunch of dilute HCl, put the shooting match of crap into a flat smooth bottomed vessel, allow all the crap to evaporate, you have mescaline salts. That's the best, but such a pain.
The companies will be very pleased.
STAY RIGHT WHERE YOU ARE, GET OUT OF THAT BED AND GET DOWN ON THE FLOOR, GET OUTSIDE RIGHT NOW, RIGHT HERE: GET DOWN ON THE CEMENT, I DONT CARE IF YOU'RE NUDE, GET DOWN ON THE CEMENT, I DON'T CARE IF ITS FREEZING! WHERES THE DRUGS, WE KNOW YOU GOT THE DRU