Go to Spline sub-object mode and in the Front viewport click on the line of the ellipse to select its spline sub-object. There is only one spline.
Activate and maximize the Top viewport. Now, go down in the Modify panel and type "1.5" as the Outline amount and press ENTER. Ellipse01 has now depth spline which will help to make the horizontal part of the fence.
Ellipse01 should be still selected. Activate and maximize the Perspective viewport. Leave the Spline sub-object mode and add an "Extrude" modifier to the ellipse.
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