Rig Builder reads a folder named "Templates" from the Rigging folder at the top level of the Characters folder. Both the Rigging and Characters folder names and paths can be defined via Tools Config.
The Rig Builder will create a new tab for every folder found within the "Templates" folder.
Sub-Folders structure:
One settings .json file created from the Helix Rigger Settings Menu that should be named settings_default.json. This file should be created from a fully setup character.
Any # of rigging .json files created from the Helix Rigger Rigging Menu with a .png file of the same name to use as the icon in Rig Builder. These files can be created from any amount or rigging applied to a character.