Player equipment only:
Not all items that you find in the player folder are actually hooked up to spawn. If you can't find an app file, you ran into one of those.
From a BaseID to an item's materials
As an example, this will use Reinforced Puffer Vest (Items.Vest_17_basic_01)
The base ID
An item's spawn code is called BaseID. It looks like this:
and will be used to spawn items via CET (Game.AddToInventory("Items.Vest_17_basic_01")).
A base ID consists out of two parts. The first one (Vest_17) determines the item, the second one (basic_01) determines the variant.
Finding the files
Head to WolvenKit and search for the first part of the BaseID:
Search WolvenKit for the first part of the BaseID
You will find at least one entity file and an appearance file.
If you find multiple files, you need to open the correct one. You can identify those by the folder path: for player meshes, the name of the last folder will contain either _pwa_ or _pma_, and the path will include either that or player.
The .app
Open the apperance file. You will see a bunch of appearances:
We only care for _m and _w right now, since they are using different meshes.
Open the array components and find the one holding the mesh:
basic_01 is using "default" material (green)
We can see that the basic_01 appearance is using the default material, and the basic_02 appearance is using the bbstripes material:
base_02 is using "bbstripes" material
To find your way through the mesh, check the guide for recoloring items!