Carrying Electronics on a Aeroplane
This answer could migrate to travel if needs be.

I have carried substantial amounts of electronic equipment as checked and carry on baggage and on a few occasions this has been most of my luggage. These flights have been NZ-Asia &amp; return with transit via Australia on occasion. I've been via Brunei, Singapore, Hong Kong and mainland China customs with such loads.

The only common 'problem', and only a minor one, has been re batteries. I carry bry batteries in carryon luggage as per IATA and airline rules. I have carried 200+ AA batteries at a time - usually NimH (for testing), packaged to avoid shorting (as per rules) in carry on baggage.This forms an X-Ray dense block and if not dealt with as below will almost invariably result in a recheck request with the batteries taken out and examined manually. I have learned that the batteries should be presented for inspection outside the bag. 

I have carried sealed wet lead acid batteries as checked baggage properly packed and labelled (ESSENTIAL) as per IATA and other rules, both from China and in NZ. Such batteries may be carried in checked luggage if properly identified &amp; labelled - if this is not done they will probably be confiscated. When carried properly labelled I have seen signs afterwards that the baggage has been opened and the batteries inspected.

I have only had "problems" with the actual electronics equipment only once. On all other occasions, even though it clearly showed on XRay, no questions were asked.
I flew into Qingdao in China during the Chinese hosted Olympic games. Qingdao was the yachting venue and China was super sensitive about possible terrorist activities. On this occasion I had effectively a full electronics workshop and components of every conceivable sort plus hand tools. My bags were last off the carousel. At customs I was politely taken aside to a private room and had to explain every item I was carrying. Quite fun :-). 

What they see is not what they get: It is probably wise to bring the equipment to customs attention regardless of it being legal.  Incoming to Dublin I was faced with a "running on auto" uper keyed up customs lady and a half circle of customs officers in a semi crouch ready to go into action. Really! I realised something was wrong. Belt bag comes out of XRay machine. "Would you please open your bag for me. Sir".  Opens bag. I'm invited to take out contents. I pull out a collapsible mini camera tripod, bought in Venice. Dual fold out metal blade legs. Screw clamp to allow it to attach to doors etc.  Adjustable height foot for levelling. Tripod head. I don't know if it was the flick knife appearing blades or an overall gun profile, but ... .
Suddenly I have a relaxed customs lady and her half circle of defenders walked away. Ah. The same thing happened on the homeward led as we passed through Australia. By then I could explain to them what they were seeing.