Actually, LSD is relatively easy to make when compared to other medical supplies. It's not easy to make in the sense that any layman can make it (in the way that crystal meth is) but it is not too difficult to make.
Delivery isnt as much of a problem as you would think. As i said, infecting the water supply of a city would be relatvely easy.
As for a better alternative, I doubt it. The only other chemical know to have the same effect as LSD and be effective with such a small dosage threshhold is DOB and DOB still isnt as strong, is much harder to manufactur, and can poison the populace. I know, Iknow. Im describing a weapon. While normally, that would be a good thing, in this case, it isn't and for 2 reasons.
1. You want as much of the populace to be alive under the effects for total chaos to be achieved. This has the 2 fold benefit of disrupting the target nation's economy (and therefore supply lines to their own military) and the fact that police forces would not be able to contain this much chaos and would, therefore, call in the military to control this (resulting in a reduction in forces elsewhere and further drain on military supplies). You effectively "recruit" the populace as improvised conscripts.
2.LSD is very hard to detect. It would be hard to prove that any chemical weapons were used at all. Mass hysteria and insanity would most likely be blamed as it would be very difficult to figure out what happened (LSD clears the body VERY quickly). This means that it would be hard to prove you broke any treaties to begin with.
As for who you are attacking, that wouldnt be a problem. LSD causes BAD trips if there is any significant stressor on your mind. a simple air strike would do it, as would unleashing a swarm of locust coupled with droping smal deposits of small arms with ammo on the streets. Imagine even 60% of the populace of new york city simultaneously suffering a bad trip due to the statue of liberty being blown up. Now picture that about 10% of them find random crates of loaded glock pistols lying around. I think you can see whats gonna happen. Remember, not everyone has to turn into a psycho killer. only a sizable enough number that it becomes too much for the cops.