Just posted you a PM for a contact in your part of the world who can likely provide WWII surplus 3-inch bomb carriers. The 3-inch pattern have always seemed to be available even here in the USA. It's the 2-inch and PIAT patterns which are hard to find. And the 4.2-inch pattern don't seem to exist anymore which is why I had to resort to making my own.
Essentially the tubes are rolled cardboard and I ordered them from a place that could turn them out with the needed inside diameter, wall thickness and overall length that I needed. I used a hole saw to cut 4.2" wooden disks which I then bored 1.5" holes in the center to hold the fuzed bombs inside. The disks got nailed to the inside of the tube while a round was inside to ensure they stayed centered and flat. Then I rolled the disks in a tin filled with lacquer so they would get coated inside and outside. It dries quickly and will make them water resistant. I used an amber tinted lacquer since it matches early to mid-war originals I had for the 3-inch pattern. They quit doing this later in the war to save on materials but I want them to last so treated mine even though the carrier represents a D-Day+ time period. The black bands are packing crate straps with crimp clips. They get nailed to wooden spacers that I cut out with a skill saw (jig saw in some parts of the world). The end caps are made from sheet metal with the edges welded on. Originals would have been pressed but you can't really tell once painted. They have a strap guide spot welded to the end that opens just as the originals had. The handle and closing strap are actually a wartime double buckle web strap that I had available here and they fit onto another short crimped piece of flat metal strap which was patterned after the type used on all other mortar bomb carriers. Quite a production but doing them over a few weekends like an assembly line made it go quickly. Also got the opportunity to teach my kids about WWII English Cottage Industry
