Boxy, don't sweat it. Nearly every large base in Afg ( including Kabul ) has a pet tailor or two who is continually employed making webbing, flags, pennants, embroidered tshirts, baseball caps, UBACS badges and just about anything else an idle mind can come up with.
When you rock up, show the tailor your capbadge ( or, better, a print out of it ), and let him crack on - it'll only cost a few dollars and you can easily get the design altered to taste. If you're feeling particularly public-spirited, you could take a list of items the Regt'l PRI want to sell and have them made in large quantity over your tour.
Personally I think that sauntering around with customised & capbadged patches, baseball cap, webbing, notebook cover etc is gayer than grinning with delight as a succession of bald moustachio'd German bikers in leather SS outfits take turn to penetrate you to the sounds of Right Said Fred.
...But a TRF would be alright.
For your information, encouraging people to unwittingly wear patches reading "Kabul Zionist Conspiracy Club" in Dari is a joke that could well rebound on you. Just so you know.