Southern Ireland is the risky one unless you know how to play their game, they did tighten up the North for a while with the introduction of xrays hunting out disposable vapes (and other things) and post office workers (mainly old people) panicked and made guys fill out unnecessary declaration forms and such,
Lately though some vendors are happy enough to send one vape at a time, says so on their manifesto,
Do a dry run with your customer, vac pack an oxo cube and a tea bag or something, take pics before you send and check its the same packing when it lands (they can absolutley open and repack your shit, print out another label and send it on, you're none the wiser.
Good luck even tho youl be grand 👍