A small GTK application that allows you to mix and match different Linux icon themes
pycons is written in Python 3 / PyGObject and can easily be installed via pip/pip3:
pip install pycons
or
pip3 install pycons
depending on how your Linux distribution handles Python 3.
Example: I use Gnome 3 with the Dash to Dock extension and I like the "Numix Circle" icons for my dock, but I'd rather have the Folder and Mimetype Icons from the "Paper" icon theme.
pycons let's you mix and match different icon-themes. It checks for installed icon-themes in /usr/share/icons and copies the newly created ones to ~/.local/share/icons.