This extension can apply Barrel distortion on the path objects in the Inkscape graphic redactor.
User can configure distortion by tuning distortion parameter called lambda in extension GUI.
Just put distortion.py and distortion.inx into your Inkscape extensions directory.
E.g., for MacOS it is ~/.config/inkscape/extensions (by default in Inkscape 0.92.2)
For detailed instructions see INSTALL file.