O Ye Of Little Faith!
I've burned my share of Esbit fuel. A month ago I bought a case of ten boxes of it to give to a friend for the PCT this summer.
I normally use a titanium wing stove. In fact that is so critical to my use that I keep a new spare one in my warehouse of critical backpacking gear. If the Esbit fuel tray is sized right for the fuel cube, then there will be only a drop or two of liquid fuel burning in the tray. In other words, it burns up almost as fast as it melts. With other Esbit burners, this may or may not be the case. I generally let the cube burn up, and I adjust the amount of heating or cooking to consume that cube that is already started. There are exceptions. While I am in camp, sometimes I burn a cube halfway, then blow it out. I will relight it ten minutes later for more cooking. I don't find it difficult to relight the crystals. Or, if I have a lot of cooking to do, sometimes I will split a cube in half, then lay a half cube on top of the old crystals from the last burn. Whichever, I normally burn up the cube by the time I break camp after breakfast. In the rare occasion when I have a half-burned cube still sitting around, I stuff it back into the Esbit packaging (plastic blister and foil). Then I stick that back into the box of new Esbit cubes. The empty wing stove is folded and placed into the Esbit box as well, and there are no sharp edges or corners at all. That box goes into a plastic bag to hold in the Esbit stench, and that goes into my backpack for transport. I can't quite imagine using expensive cuben fiber anything just to haul Esbit around.
So, for me, a suitable Esbit container might be a plastic bag with my aluminum foil wind screen wrapped around it.
In a completely different situation, I carry two rounds of Esbit fuel with me in a real emergency kit. All it has are two rounds, a steel bottle cap as a fuel tray, a book of paper matches, a square of foil as a wind screen, and a folding handle titanium Sierra cup. There, I am only interested in heating one or two cups of water, and I don't worry about Esbit liquid or crystals or anything like that.
–B.G.–