hi there,
joe whitten makes a 2x4 in a slim configuration.
4 shaft holes on top and 2 butts on the bottom.
kind of a rounded triangle.
heres a pic from his site. http://www.whittencases.com/The_4x2_Lite.html#20
i have one coming in september.
for profile thickness, I would have to say either an it's george, or justice prolite for hard cases, (i think jb cases are nearly the same dimmension as justice...).
definitely the Fellini, Engles. It's george, GTF style cases have the smallest footprint. After that you move to the Justis, Jay Flowers, JB and Instroke cases. Then you go to Whitten, Porper, etc.
The It's George style cases like: It's George; Thomas; GTF; and others are very slim style of cases and offer excellent protection. Also, you might look into butterfly cases as an option.
However, the slimmest 2x4 cases are those without pockets. If you are interested, I have a nice Whitten 2x4 w/o pockets & a rare Chaz Dillon 2x4 elephant hide case w/the JB Cases interior w/o pockets, but that cue has a couple of extra leather pouches that hold my bridge head and tip tools & chalk that hang off one of the rings.
Here are a couple of pics of the Chaz case (I have plenty more if interested):