TSA is pretty whimsical with hand tools, FYI. i recently had my favorite pair of wire strippers confiscated, after probably like 100 flights with the things. i guess the length from the tip to end of handle was >6in, which in one agent’s estimation was sufficient for attention - despite the “business end” being like 1.5in. ah well.
agree, “synthesizers” aren’t a particular problem. literally everyone has gadgets. they seem to care more about the various bits of steel or aluminum that tend to accompany them. i get my stuff singled for bomb-sniffing probably 4/5 times, and i think this is basically because of opacity to x-rays.
it was actually harder in the old days, when traveling with personal electronics was “weird” and they would ask you to “turn it on.”
(my dad’s unhelpful reaction: “i could totally build a bomb into a working radio if i wanted to! you moron!!!”)
i would also like to second the importance of memorizing and/or carrying a hard copy of section 403 of FAA Modernization and Reform Act of 2012. this applies to any kind of musical instrument that can physically fit into overhead bin; in my case it has been invaluable for violas and “travel” sized acoustic guitars. board early when possible.