We provide the 3D models of all weapons which are compatible with Weapon Finishes.
You can download the weapon models from Lambda Downloads https://lambda.tf/downloads/category/2-content-creation/file/2-weapon-knife-source-models
In addition, if you wish to use the default materials and build upon them for your paint kit authoring, you can download them here: https://lambda.tf/downloads/category/2-content-creation/file/4-weapon-knife-default-materials