Hi shokan - you basically need to get some curves drawn in which follow the paths for those planks.

Once you have a curve framework created you can then construct planks from curves using the Construct > Sweep command.

One basic approach for creating the curve framework is to start by drawing a path in the Top view, then turn on the curve's control points with Edit > Show pts and then select different points and move them upwards in the side views to modify the curve from a planar flat curve into a 3D path curve.


Then once you have some path curves you would draw in some rectangles as the profiles for the sweep. If you want non-uniform planks with wider areas in the middle, put in multiple rectangles as the profiles with some larger ones in the middle.

You may need to place the rectangles directly on to the path curve to control how they are rotated around the path - the Transform > Orient command can help with repositioning a rectangle that was originally drawn flat on the Top view on to the 3D curve perpendicular to it:
http://moi3d.com/2.0/docs/moi_command_reference8.htm#orient

Here's a quick example where I've done what I described above, also see attached 3DM file:




- Michael