This video shows how to make and replace props for source engine games.

Requirements:
Blender: https://www.blender.org/download/
Blender Source plugin: http://steamreview.org/BlenderSourceTools/
Crowbar: https://steamhost.cn/steamcommunity_com/groups/CrowbarTool
VTF Edit: https://nemstools.github.io/pages/VTFLib-Download.html

Optional:
Notepad++: https://notepad-plus-plus.org/downloads/
Notepad ++ VDF Language (Syntax highlight for CQ file and more): https://github.com/ReverendV92/NotepadPP-VDF-Languages

Map Decompiler (BSPSource) : https://github.com/ata4/bspsrc/releases
Open this tool, put a map's BSP into the list and decompile the map.
You'll get a VMF file that Hammer World Editor can load. You can then find props you want to edit.

Collision model guide: https://www.youtube.com/watch?v=NxmCzkQBXrc

Dead 4 Mods Discord: https://discord.gg/4qtmzBP
My Discord: https://discord.gg/5eDA7CE

I also got Paypal[paypal.me] for don't-ations.