Embedding Unity in Windows application

How to embed unity in my windows form? or rather how to use unity3d classes in my windows application developed in visual studio in order to render 3d objects?

This has been covered in: Is it possible to start Unity from a C# project ?

As Lucas pointed out: The possibility that's available is using the Unity Webplayer ActiveX control - but it's a non-documented and non-supported solution, so "use at your own risk" and be aware of its limitations.

Another question to the same subject was: Is it possible to build a standalone .net application that link UnityEngine.dll

I'm not sure how much success people have with this, but you could try taking the Unity webplayer activex control, and embedding that. You're likely to experience some friction along the way, but as a first thing to try, I would try this.

You can try to embed unity player’s window by using "-parentHWND " command line arguments.
Here is an example how to do this without dealing with the webplayer activex (unfortunately i’m not the biggest fan of the COM technology).