They're still making them.
Gun ownership (for modern guns) is a real hassle in Thailand, with licensing, registration, etc., and few licensed dealers. The hilltribes (I believe) get an official blind eye turned to their do-it-yourself ML types - I never saw one with the mandatory registration letters or numbers stamped on it.
I did see a good number of blacksmith-grade cartridge firing single-shot pistols and a few revolvers (I had a .22RF revolver made to look like a S&W: it was a 7-shooter and worked, sort-of, but had to be manually rotated between shots - It had a spring and ball bearing in the frame and detent dimples in the cylinder - was unrifled, and the chambers were bored with a slightly-oversized twist drill, so I had to wrap the rounds with paper to get a better fit and ignition - it shot lousy, but it did shoot. Neither did it have any mechanical extractor: you get the idea). Such guns were generally pieced-up by brazing various pieces of steel together to make the frame, were break-open types, and never rifled. I did shoot one (once) chambered for .45 Auto (!), which was a victory for curiosity over good sense.
The pictured ML specimen appears fairly recent, without the 'patina' that comes from much use in the tropical forests and little care or cleaning.
They are still sold to tourists in hill country areas.
Another class of more modern design firearms I saw fairly often in unlicensed hands was Chinese copies of European semi-auto pistols, from fairly neat Browning 1900 .32 autos to the ever popular (in Asia) Mauser C96: none of them would fool a user who ever had access to the real things, but some of them did work fairly well.
mhb - Mike