Thailand, lucky you. My son was there earlier this year, with his Thai friends.
There are a couple of interesting videos on YouTube on making flashers. One describes how to use the mylar bladder from a wine box to make a squid-like terminator, not unlike the one pictured above.
I only bought a wine box once in my life. We had a lot of guests over but then only one drank wine and then only a few sips. Never again!
There is another by Dan Mann and friends that show a few options for making your own but they seem to have access to parts not readily available in GB.
One video on using flashers mentioned that shark tend to get caught up in ladder-style flashers. Imagine having to sort that out!
Good news, Spearfishing.co.uk have Rob Allen flashers on deep discount. Bad news, they are still eye wateringly expensive. Sadly the pound is much weaker these days than when I first started out with RA gear. They look great, I would love to hang a couple on the wall for decoration

. I'd love to try fishing over flashers but I think not much use for the murky waters and small fish around most of the UK these days ( but feel free to correct me if you know better ).