Originally Posted by
catbeef
dunno about customs for swedish citizens re-entering sweden, but when you come back to the uk (i think everyone goes the same way, i have to admit i've never paid attention now i think about it) you just waltz past customs. you only go in if you decide you have something to declare. i have never once been asking aside to have a look in my bag. i have travelled a lot and with a variety of bags of many shapes, sizes and colours.
also it would simply not be feasible for customs to investigate every single bag on the off chance someone is doing something naughty, unless you're at a tiny airport with bored staff, i guess. don't think sniffing doggies are trained to sniff out unpaid tax items :P
and then, a very old and simple trick. throw the boxes/receipts away. tuck the parts into your clothes or some other safe place (hand luggage!) and if asked (which is already established as unlikely, in my english experiences) you simply reply something like 'yeah i took my pc to this lan in america it was great i won $50 playing in a worms armageddon competition!'