Step 1 - Export your model from blender in an FBX format
Step 2 - Make all textures into PNG
Step 3 - Install VRChatSDK https://www.vrchat.net/home/download
Step 4 - Install Unity (Version 2017.4.28f1)
Step 5 - Open Unity and drag drop VRChatSDK into the workspace on the bottom middle, it will give you a popup confirming to import everything, click accept
