- Choose Files->New , thus starting work in a new file.
- Rename the layer 'Layer0' to 'pipe1' and create two new child layers "inner" and "outer". Set 'pipe1//inner' as layer to use with a <Double-click>
- Choose Geometry->Create->Point and enter new point (0, 9)
- set 'pipe1//outer' as layer to use and create the new point (0, 11). Press ESC to conclude the creation of points.
- From the Copy window, select Points and Rotation . Enter an angle of 180 degrees and from the Do extrude menu, select Lines . The axis of rotation is the x axis. Enter two points defining the axis, one in First Point and the other in Second Point , for example, (0, 0, 0) and (1, 0, 0) , check Maintain layers , and set Multiple copies to 2.
- Click Select and select the two points just created. Press ESC .
- Create a surface: choose Geometry->Create->NURBS Surface->By contour and select the four lines. Press ESC twice.
- From the Copy window, choose Surfaces and Translation . In First Point and Second Point , enter the points defining the translation vector. Since the pipe section must measure 40 length units, the vector is defined by points (0, 0, 0) and (-40, 0, 0).
- From the Do extrude menu, choose the Volumes option, and set Multiple copies to 1.
- Click Select to select the surface. Press ESC to conclude the selection process.