Blender is the primary tool used by NWN content creators for models. This is because the 3dsMax and older GMax tooling is now severely out of date in some regards.

Note that Blender isn't particularly useful for editing emitters and VFX; although to be honest 3dsMax isn't much better, and in both cases ASCII editing by hand may be preferred.

Main Tool Usage

Get Blender here: https://www.blender.org/

Get Neverblender, the main plugin for working with MDL files, here: https://neverwintervault.org/project/nwn1/other/tool/neverblender-28

You'll also usually want Clean Models: EE to decompile existing models properly: https://neverwintervault.org/project/nwnee/other/tool/clean-modelsee

Additional Addon Recommendations

Blender addons for game asset workflow.

Free:

• Machine Tools - This is the first addon anyone should install and master outright essential modelling and grouping tools https://machin3.io/MACHIN3tools/
• Textools - This addon adds tons of tools for unwrapping https://blenderartists.org/t/textools-for-blender/700811/903
• F2 - Comes with blender, makes building polygons faster with F key in edit mode.
• Looptools - Comes build in blender, many modelling tools for relaxing vertices, making circles with selected verts and spacing vertices to even length
• Meshtools - Comes build in blender, modelling tools in one place behind right click menu in edit mode.
• Copy attributes menu - Comes build in, ctrl+c now have new dialog with huge list of things you can copy from one object to another, essential.
• Bsurfaces - build in blender. you can draw lines over your mesh to create polygons used mostly for game asset retopology workflow.

Paid - recommended to wait for sale periods for them to be made cheaper:

• Zen UV - One of the best unwrapping addon for hard surface models, fast workflow. https://blenderartists.org/t/zen-uv-for-blender/1235124
• UV Packmaster 3 - You hate UV island tetris? We all do this addon even though pricey saves you literally hours you would be otherwise spending manually playing uv tetris. https://blenderartists.org/t/uv-packmaster-efficient-uv-packing-solution-for-blender-c-based-multithreaded/1102737
• Hard Ops - Doesn't need introduction every blender user knows it and uses it, bestseller and for a reason. https://blenderartists.org/t/hard-ops-thread/657591/2

Tutorials

See the Tutorials page for a list of Blender and modelling tutorials. Even if the tool isn't blender (eg it's for 3dsMax) you may still find useful information.