Heres my final version of the image
As you can see on this image the sugar is flying from one cup to the other and there is motion blur as well.
And last but not least the sugar cubes are building a perfect curve path.
I thought about how can i do that. First thought was that I take a image and do the sugar as CGI, but that is not how it was done. Then i went to the studio and i tried to hang the sugar with little fishing lines but it was impossible to line up the sugar cubes in a curve like on the image and the angle of the the cubes even weren't right as well. So I had to come up with another idea.
So the now that i know how its not done I had to get it working. Then I came up with the idea using plexiglass and sticking the sugar cubes to the plexiglass.
And here is the setup image:
As you can see in the image the sugar is now glued on the plexiglass. The plexiglass is a little bit behind the coffee cup and over the sugar cup. And thanks to the perspective if the edge of the is removed you cant really notice where the sugar cubes really are.
Then I toked another image of the setup but this time without the plexiglass and with coffee in the cup.
The rest of the work is just to put these to images together in Photoshop.
Here is the Layer setup in Photoshop:
The first layer is the image without the sugar, the second layer is the image with the plexiglass, the next 6 Layers are for the motion blur of the sugar cubes i used the motion blur filter. The nearest cube to the sugar cup is the most blurred one and if you go nearer to the coffee cup the blurriness is getting lesser and lesser.
And that is how they did it.
May force be with you and never run out of coffee.