years ago (5 or so), i was flying back from thailand to germany with a metal tool box in my hand luggage, with fixed installation of an ATX power supply, a 5 port network switch, 4 RPi, everything was wired up. from the outside of the metal tool box you saw a power plug, ventillation holes, 4 BNC connectors for Video output and a network connector port.
the only thing i had to do at security control gate in thailand was, to open the metal box.
the only thing, what the security man was asking then, was:
he: "is it really working?"...
he: "aha!... "ok"...
even my constuction was looking a litte bit like a bomb with all the wires, stacked installation and so on.
i can't beleave that i was doing it. today i never would do this again. too big the risk to not pass the security gate.
but at that time on the way home, i hadn't enough space in my baggage anymore.
but i beleave a single RPi in a nice looking case (or even in a crappy) can still pass the security control gate without problems.
i was passing airport heathrow months ago two times with my backpack full of computerstuff, extra cables, power adapters, battery power bank.
(they did a wipe test against explosives - but that had nothing to do with the stuff i had in my backpack. they do this randomly and takes only few seconds)
PS: i am always worried or scared about losing my data of mobile phone, SSD, SD cards and USB memory sticks over the time, when they pass the X-ray over and over...