Draw a small circle using Ellipse tool pressing shift while creating will give you a perfect round.
use the pen tool to read a path something like this with stroke edges selected as straight as seen in the following image
Repeat step 4 this time add a central node as well which will help you achieve a better shape by adjusting it using anchor points
Select both the paths and go to object>Expand in the menu which will show up the Expand window , select the stroke expand and hit ok….
now select all the assets and right click and group . This is important as now when we are going to apply a 3D effect to it illustrator will take it as front face….
Now go to Effects>3D>Extrude and bevel with the group selected
Play around with the options in the window i have chosen 42 perspective , extrude depth 25pt , and rotate dimensions accordingly . You might like to keep the preview checked and view what is going on
here i have taken the image to photoshop to give it some gradience and play around with it since it is already done you can now do anything with it!
The finished RSS 3d icon