I can’t find any tutorial either in unity3d or blender.
I want to add to my drone in the bottom a camera that will rotate 360 degrees and then i will use the unity3d camera to look through it. But how can i model the camera first ?
If you are talking about a 3D model of a camera you will need to learn how to model it yourself or find one already made that fits your needs. You can try https://www.turbosquid.com/ , https://archive3d.net/ or any other 3D models website.
If you are talking about how to model that camera, I would suggest modeling the fixed part of the camera, then you create the moving part of the camera like a sphere and put it as a child of your camera so that it follows its rotation. I’m thinking something like this http://www.dronesglobe.com/wp-content/uploads/2017/04/yuneec-q500_web-2.jpg
