It could be made with a larger 12 cm billy though, I found a perfect drainer that fits the 12 cm zebra with a very good tight fit for packing away. It was cut in the same way as Gary did his, and I can also fit the 10 cm straight inside with a lid and wire bail arm. I also have a trangia pot support and burner, a finger guard from the back of a computer and a trangia pot handle, a small folding cup and I usually have my wooden spoon in my back pocket. Knife and fire stick baldricked so I have everything I need to make a brew, chuck the lot in a small bag with a nalgene bottle and a few sarnies and I can be off for a good day hike.
If anybody needs one of the 12 cm drainers for a hobo stove, give me a shout and I'll see what I can do. I think they were just under 3 quid, they are coated in what I thought was enamel but it burns off to leave a lovely stainless steel underneath.