I'm working on a new plugin, lets the user add settings to the Print Settings tab for materials on the Materials pane of the preferences. At its simplest, it adds the "Flow" parameter to the list of print settings for materials. The plugin also adds Extensions -> Material Settings -> Configure Material Settings. This will open a dialog that lets you configure what settings will be available, so you can add arbitrary settings such as Z Offset and Linear Advance Factor (both requiring an add