Thanks to all for the replies, that's good info. Hopefully there'll be the area Brighton Girl alludes to that'll mean the cases can be scanned prior to disappearing to the baggage equivalent of a torture chamber in the bowels of the terminal, where the screams of Samsonites being violated echo through the dank corridors
As the kit is in metal flightcases secured with hasps and padlocks, if there is no scanning at c/i, I guess I can try to leave the padlocks open and a note attached to the case to the effect of:
Dear TSA,
To save wear and tear on your boltcutters I've left the padlocks open. Please feel free to search the case, I'd appreciate it if you could then secure the padlocks. Thanks.
Long shot I know, but if it comes to it, it'll be better than potentially having the cases bent and hasps destroyed. I'll let you know how I get on.
Re the cable ties, Halfords do sell them, but are expensive. If you can get to RS or Maplins they're much cheaper (and still come in the fabulous colours).
Thanks again to all,
Cheers,
Bob