That's a very nice one. Can you tell me what's the most difficult modeling part out of it? (I'm trying to get any insight about modeling here)

Also, the 'un-smooth' gradation (what do you people call it in english?) on the top left of the picture seems still occur in KeyShot. I've been bugged with that too for quite a while. How to solve it in KeyShot?

Thank you very much in advance for replies and pardon my English.