tutorial i will show you how to create abstract design element. The most important thing that you learn is not how to make this element, but how to apply symbol (map art) on the 3d object and how to use blend function. Now create rounded rectangle using rounded rectangle tool, if you dont see it, left click and hold until you see popup with new menu. Simple click that tool and then click anywhere on the document. When options appear, choose width and height of From the spacing popup menu select Specified Steps. This function will insert number of object copies in between those two that you draw. Bellow you can see that i have blended in 10 rectangles between first two. It doesnt matter how much you will choose, make sure you see some gaps between rectangles. Now you can simply choose diferrent number of object if you want. With all rectangles selected, go again to and hit ok. After you expand it you no longer be able to choose steps to blend in. You now have expanded it to single grouped elements. You have to do it if you want to edit seperate elements. Select all rectangles and make a copy of it like in the previous step but now not to the right direction, but to the bottom. While holding Now you should take a break before moving on to the next part, because reading from computer monitor is not good for your health. Take a coffe break :) Now that you have previuosly created element in your symbols menu, create another rectangle with width and height of arround 500 px and corner radius of 10 px. You can simply create it by clicking on the rounded rectangle icon and draw it with mouse or with single mouse click and then choose options. You will see only the symbol that you have created in the first part of the tutorial. The big rectangle now is invisible and the symbol is now conected to that big rectangle. Now back in the You have succesfully applied symbol on 3D rectangle. Now press right mouse button and select Ungroup. Keep doing that until you see then hit it. Then again ungroup all element. By doing that you will remove all trash that 3D function has created (invisible big rectangle). Source.