Building KDE Plasma 5
Follow the build instructions for KDE Plasma 5.
Apart from the packages mentioned in the instructions, I had to install some extra packages:
libjson-perl qttools5-dev-tools qtdeclarative5-dev libqt5webkit5-dev libxcb-damage0-dev libxcb-composite0-dev libxcb-xtest0-dev libgtk-3-dev libqt5multimedia5 libinput-dev libepoxy-dev libqt5declarative5 xsltproc libnm-glib-dev libnm-util-dev