Recently, I started to use Kubuntu 15.04 with Plasma 5.
Although I had some minor issues in the beginning, I am really pleased by the new look and some of the new features. One aspect that I particularly like is the new icon set (called Breeze). It is elegant and coherent.
Also, I liked the idea of having versions of the icons designed specifically for situations where they are small, such as in the taskbar. Those versions are monochromatic and, usually, with less details than the regular ones.
But the icon set does not have small versions for all icons. As a result, some of the icons in my taskbar were coloured and others monochromatic. After some search, I found the guidelines for the Breeze icons and adapted icons for some applications that I usually include in my taskbar. Here they are:
In order to use them, download (right click, save link) and copy the files to the folder /usr/share/icon/breeze/apps/software-small.
I will update the post every time I create a new icon.