Let's face it, Engineering isn't quite up to par with the other professions. I, however, have the solution. It's simple. Blizzard already has the mechanic in place!
We have Runic Healing (Mana) Potion Injectors. So as a well stocked raider, you carry anywhere from 20 to 60 of each in 1 to 3 stacks. However, as a DPS in a guild pushing for things like 6 minute Malygos, there is the nifty introduction of Speed Potions. The problem with these is simple, they only stack to 5.
I have, in my bags:
13 Flasks of Relentless Assualt
33 Speed Potions
20 Runic Healing Potions
With our current ability to stack that comes out to:
What I propose, is for the introduction of one schematic, and the revision of another.
The Multipurpose Injector
: Converts 20 of the same type of potion into combat injectors
: 12 Saronite Bars, 12 Cobalt Bolts
: Converts 20 of the same type of flask or elixir into one compact, easy to carry container.
: 12 Saronite Bars, 4 Titanium Bars, 6 Cobalt Bolts
It's expensive, and requires 20 flasks, so it's not like everyone will have these. But for those willing to invest, it'll reduce 11 stacks of bag space into (assuming I started with numerals of 20, and worked down to my current values)
It will have no effect on class balancing or PVP balance. It will be another convenience thing (which is what Engineering is all about) for the player.