I guess these are the types of threads that get me to come back...
I like the above designs simplicity and I think it's cool that they can stack, although I'm not sure of the purpose of stacking.
What I don't care about the 2D6 setup is that it requires...well, 2D6. I feel that a tray that has two dice is cumbersome and crowded. Imagine grabbing one die to flip without bumping another that is really close. To get around this I prefer using 2 different colored dice. For example, when a white die is in the tray then that means there are a number of torpedoes equal to 6 + the number on the white die. Once the torpedo count goes below 7 (i.e. less then 1 on a white die) then I swap out the white die for a black die to count the final 6. Thus 12-7 is represented by a white die an 6-1 by a black, or whatever pairing of colored dice you desire to use.
Also, I've found that you want the tray to be relatively deep, about a quarter of the dies height. This makes it hard to bump the die lose, but easy to remove if grasped. Lastly, to keep the base spacious I prefer using a single 8mm die because it's just big enough for adult hands, easier to obtain cheaply then 10mm dice, and it's unobtrusive, meaning it won't stick out to much if you choose to actually model the torpedoes.
I have ordnance markers for Full Thrust fighters that I made that follow the above principles and use an 8mm black die. The die is the perfect size in my opinion, as it doesn't get in the way of the fighter stands, but it's easy to grab and flip:
And I made a 1cm square one for BFG that I have not cast duplicate of yet. It uses the 8mm tray as well. Just imagine this base finished with 3 little torpedoes on it like the above FT fighter base:
