I went through a screening with a "robot" - in quotes because it was literally a breadboard with a bunch of wires sticking out of it, a battery and a squarish box. Didn't even have to open the bag to show the agents what it was, went right through the scanner with no comment. And I was nervous as hell cause I was sure I was going to have to explain it, maybe even show that it worked. But nope, not a peep.
How white are you, out of curiosity? What's your demographic look like, and how closely did it match the screeners? Seems like if you were nervous that would be additional weighting in the direction of you being questioned, so the additional weighting doesn't seem to have motivated anything.
It was tucked into a backpack along with quite a few other things (including 2 soldering irons, actually). I don't remember exactly what else was in the bag as to whether there was anything that could have looked like fuel in the scanner though, so fair point potentially. However, while it wasn't the point of my anecdote, I'm also fairly confident being white was one of the factors that played into zero questions being asked.
I am white male, and it was in a Southern US airport that was also very white. While that wasn't the point of the anecdote, I'm also fairly confident it played a large part in there being zero follow-up questions.
I've taken a lot of messy electronic prototypes through security when traveling for work. The TSA has never cared. My camera bag, on the other hand, seems to get some baggage screeners very excited. Something about the glass being opaque to x-rays? But most screeners don't care.
It would be pointless for the scanners to ping on copper, ABS, or batteries because every single flyer would have to open their bags and buttholes. It's the C4 and other pyro that they want to know about.
