[header] How to draw curved surfaces in sketchup [title] Create a set of tangent arcs. [title] Click on the move icon and make a copy and move it a small distance away. [title] Connect them on each side. 
[title] Use the push/pull tool and pull it out to the width that you want it. [step] Hold down ctrl, click on the eraser tool and erase the lines that you see on the top and the bottom so the surface is' smooth'.