How can I make Unity 2D launcher icons smaller?
Is it possible to change the icon sizes of the buttons in the launcher used in Unity 2D?
At this moment, here is no way to change the launcher width in Unity 2D, as you can read here:
I suggest to register to this bug on launchpad, that is the related feature request:
Note: the are few other options you can choose, see question How do I configure Unity 2D?
You might actually not need to be using Unity 2D. I found that if I tried to log in to just ubuntu I would get just the background but no Unity 3D; 2D log in worked fine. However if after downloading Gnome-shell I could log into "Classic no effects" then in a terminal window type "Unity" and I can get the Unity 3D shell working that way and be able to change icon size etc from compiz. I'm sure there's a more elegant way of doing this but the workaround worked for me.