Look for batteries... Look for wires... Look for these things on devices or packages left in public places or next to vital infrastructure... Any of this ringing a bell?
Also, from the footage I've seen, these signs are most visible -- and most effective -- seen at night. In the dark, the illuminated character is visible, and the "frightening" bits and pieces are not. The creator did not intend the devices' bomb-like nature (which I still contest) to be effective, but the appearance of an illuminated character in the dark.
And, note, that the problems happened during the day. These things were designed to be left out in the open 24/7. The designer is responsible for what they look like during the day and during the night.
Also, if I were designing a sign, I would have a photosensor to shut off the LEDs during the day to conserve the batteries. Was this unit even on during the day?
You're simplifying things to the point of absurdity. In equally simple terms, in order to blow up, there has to be an explosive in addition to the wires and batteries. There wasn't any attached to the Lite Brites. There's no there, there.
And, note, that the problems happened during the day. These things were designed to be left out in the open 24/7. The designer is responsible for what they look like during the day and during the night.
Your contention was that the creators' intent was that the object look like a bomb. Mine is that the creators' intent encompasses what it would look like in the dark, not to an up-close examination during the day. If you want to talk about responsibility, that's another matter and we can take it up. But I was replying to your position on the creators' intent.
Also, if I were designing a sign, I would have a photosensor to shut off the LEDs during the day to conserve the batteries. Was this unit even on during the day?
Yeah, right. Build in a photosensor to conserve two dollars' worth of batteries. Why not put in a wireless access point and install Linux, too?