Any problems taking arduino(esque) devices through airport security?
It will depend on your particular country of course. Check the rules on cabin baggage.

In Australia, Arduino boards should pose no problem. It is best to not take any batteries or tools with edges (screwdrivers) or heavy tools (wrenches). In case they do want to have a look, place the boards at the top of your bag for easy access.

I have traveled to Europe from Australia with half a suitcase full of large PCBs with no problem. The only time my bag was opened was when I was carrying a tea pot stand, which was in the shape of a tea pot. Apparently it looked like a gun.