While the base Aurora Toolset can allow a module to be created (with areas, creatures, conversations, items, stores and scripts) you might want to use custom content in your module or create custom content.
This can include new models and animations (for creatures, placeables, items, VFX and tilesets), textures (for models, but also including portraits, icons and special colourable PLT textures), game data (spells, races, classes, feats, item types and much more), sounds, music, shaders, TLK files for text, movies and several miscellaneous things.
Getting Started with Custom Content
For an introduction on how to add a simple placeable to the game files, see: Introduction to Adding Custom Content to a Module. For hakpacks to bundle your custom content for release see Introduction to Hakpacks.
For more tutorials see Tutorials covering a wide range of topics.
Custom Content Tools
See the Custom Content Tools page for a more exhaustive list, here is a basic rundown for essentials;