they will be too busy looking for water bottles
if you are worried about the x ray thing.. their x ray can't much tell if you are bringing a normal cart or a flashcart..
also, no point in hiding it, hidding stuff may trigger false positives or some shit..
(like that old saying, the best hiding is in plain sight)
i never traveled outside europe, but within europe i never had issues with flashcarts or computers or stuff.. they just ask if i carry "big devices" for example a laptop or tablet and ask to put in a separate bin.. sometimes i even put my 3ds and the box with the cards into the separate bin, never had a problem.
carried both ds and gba flashcarts. and i remember once i even carried all my carts (20 ish) they didn't care..
and i one of thoose guys who get super nervous even if i don't do anything bad or wrong i am just nervous that they may think i am a bad guy or something
(like when you exit from a store and you pass by the security dude with no purchases)