No idea if they would ship just a thread protector over to you, or if you would even want to pay shipping. PVA makes thread protectors to cover just about all barrel diameter to protect the entire shoulder. Have a few of them my self and they are all I buy.
patriotvalleyarms.com
Edit to add. You may just be better of going to a machine shop with a simple drawing of what you want exactly if you can't find a company in your country that sells what you want. You may pay a little more though. Would get it made out of stainless, or even brass like mentioned. Not sure I would do aluminum my self, but don't see why it wouldn't work for at least the life of the barrel or longer.
Thread length from shoulder to crown, OD of the protector to match up to the OD of the barrel at the shoulder, and of course drilled and tapped at 5/8-24. Have a couple flats put on for a wrench or knurled so you can get it on and off would be a plus. I don't use a wrench on my PVA protectors, I just finger tight as I use a suppressor. Most times the threaded part is all within a certain length that most protectors cover, or are a little longer which does not hurt anything. Just measured four barrels for the length of the threads and they were all between 15mm and 15.8mm so get it made at 16mm long and you should be good for your current barrel, and any new barrel you get. If you do get a machine shop to make one, may as well get more than one in case you loose it, or need another in the future.