Arguably the biggest hurdles to importing any mods to NR2003 are that this needs to be done through plugins for something like 3DS Max and the tools necessary to compile the models, are still being held closely.
Mystical's video series on creating a mod, sort of explains the internal problem; which is why mod makers are few and far between.
I have the tutorials all indexed here and setting up 3ds Max 8:
https://www.adrd-forums.net/index/forums/nr2003-mod-creation-tutorials-and-help.33/
The days of secrets and tools held behind the walls have been long gone for a good while now. In the most basic setup anyone can make a mod from start to finish with just these core tools:
- Modeling: Blender 2.8/3.0+ (free)
- Textures: Gimp/Affinity/Photoshop/etc (free to paid)
- Mod Setup: 3DS Max 6-8 (canot use newer version unless one day the Papyurs plugins get ported to them or are able to be used in another 3d application like blender) (technically coasts money but Autodesk no logner seels 3ds max 6-8, you'd need the tool already or the archived zip of the old version)
- Mod Scripting/Coding: Any text editor, Notepad++ recommended to edit quicker and can use my papyrus Language addon (free)
- 3DO Compile: Make3DO.exe (comes with Sandbox when you install it
- Texture compile: WinMip2 (comes with the tools papyrus released)
All that really stops anyone from making a mod is how much work they are willing to put in and learning the process now. Same with track making, wish lists are nice but only they can be the ones to make the content in NR2003 they ant, no one else is going to do it (as I've said like a broken record for years now lol)