We do not yet have full details on how the booby traps that were rigged in his apartment were set (and we might not ever get them), but access to explosive materials, while not entirely impossible, has become much more difficult since the Oklahoma City bombing. Clearly, he did not use ANFO, but other highly destructive materials were in place, and it is fortunate these were not activated.
Technically, the AR-15 rifle and the drum-type magazine are legal for civilians to acquire in Colorado, as is the battle armor. And the canisters, so far as may be determined, were not tear gas, else the patrons of the movie house would have much more incapacitated than they were, and there were no reports of anybody being treated for the effects of tear gas or other highly irritant inhaled substances.
This was a highly planned and detailed operation. Perhaps it was sufficient to say one person COULD have done it all, but there is plenty of reason to consider that other persons or agencies expedited the acquisition and placement of the hardware used. And that is where this whole operation becomes just a little creepy. “Regular citizens” do not plan massacres. But a devotee of the “Occupy Black Bloc” operation surely could.
Anarchy is an ugly fact to have to live with.
The cops have mentioned that there was ten gallons of gasoline in the apt. Regardless of what else might have been there the gas alone, properly vaporized before ignition, would have taken the walls out of the building-——call it a fuel-air bomb. It would be pretty equivalent to ten sticks of 40% dynamite. Been there/done that and it is powerful.