Adjust the circles you created and the surface will be adjusted. Play with the scale and Y translation of the circles until you get a shape you like for the tree trunk. I ended up with the one below.
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Now that I have the shape I want for the trunk; I will convert the Nurbs into Polygons. Make sure to check the options box to adjust the result you will get.
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I found the options below to be the best output for what I wanted.
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Now the trunk is polygon we are going to cap the top. Activate the Select Border Edge Tool.
