As I surmised, they are art students ("performance artists"). My daughter was an art major and I have run into a lot of these people over the last few years.
They are self-absorbed, contemptuous of society, overly concerned with appearance over substance, and generally unable to relate to the general public.
I still maintain that seeing these things in daylight one would be unable to see the character they were portraying, and with the batteries and wires and the fact they were attached to infrastructure, it is easy to see how people got alarmed.
Of course, I am simply stupid, according to all these cool people who can INSTANTLY distinguish bombs from harmless items, and who watch cartoons for entertainment. HA!
The level of hostility and rudeness on this thread is disappointing. No better than DU.
It's hard not to be contemptuous of a society that has three dimensions. We have five. Thousand.