how to present a 3D Game Object as a UI?

I am basically making lock picking system like the one in Assassins Creed Unity. As in this video
as seen in the video the inner cylinder that appears on the screen looks like a UI element. I made the system (or the mini game) on a 3D object and it will be hard to convert it into UI as the designer will get it rigged and animated as a 3D object.

what I want to do is to make that 3D object Always appear in front of everything. what is the best way to do this?

You can use two different camera and different layer masks. One camera for your gameplay and other is for your ui elements or in your case 3d object. Simply add a new camera and set it’s position to see your 3d object after that add layer masks. Like photoshop you can use layers in a number of ways in unity. I can say that it is the best practice to make a 3d object layer.

Here you can learn more :

If your Canvas Render Mode is set to Screen Space - Overlay, there is no way to render an object in front of it.
You must set the Render Mode to Screen Space - Camera or World Space, and than place your object in front of the UI.

If you want your 3D object to be rendered in front other 3d objects, you might want to write your own shader with ZTest Always