НЕУЖЕЛИ НИ КТО НЕ ДЕЛАЛ НАКЛОННЫХ СТЕН?

Видимо, это единственный способ, ведь если посмотреть в базе знаний autodesk http://support.autodesk.com/enu/navigat … &last=

выбрать knowledge base (запрос "sloped wall"), то мы видим:
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You want to create a sloped wall, but there is no wall style for sloped walls.
 

Solution

While there is not a wall style for sloped walls, you can use the Sweep Profile command to create them.

Create the profile

In Plan View, create a closed polyline that corresponds to the sectional view of the sloped wall you want to create.
On the Desktop menu, click Style Manager.
In the Style Manager, right-click Profiles and click New.
Enter a name for the new profile.
Right-click the new profile name and click Set From.
In the drawing window, select the closed polyline you created in step 1 and follow the command line instructions.
In the Style Manager, click Apply and OK to accept changes and end the command.
Apply the new profile

Select a wall, right-click, and click Model Tools > Sweep Profile.
In the Profile Definitions dialog box, select the profile created in the first procedure and click OK.
Enter the wall style component index on the command line.
Note: If the wall style contains more than one component and you want to apply the profile to more than one component, you must apply the new profile to each component
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А это по поводу вставки окон и дверей:
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Windows and doors do not properly anchor into sloped walls created by the Railing routine. 

Solution

Use a subtractive Mass Object to create a void in the sloped wall.

Create a Massing Element that has the same dimensions as the door or window to be inserted. To do so, open the Concept menu > Mass Elements > Add Massing Element.

Place the Massing Element in the location on the wall where the door or window will be placed.

From the Concept menu, select Mass Grouping Tools to create a Mass Grouping.

Right-click on the Mass Group and choose Attach Elements.

Select the sloped wall and the Element from step 1.

When you are finished selecting objects, press Enter.

Right-click on the Mass Group and choose Show Model Explorer.

Expand the tree to display the individual elements, then select the Element from step 1.

Right-click and select Operation > Subtractive.

This creates a void in the wall into which you can now insert your door or window.
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Вот, на мой взгляд, и все по этой теме. Но, может быть, Вы больше найдете.
Прошу прощения, что не перевожу на русский - английский у меня далеко не идеален, могу ошибиться, лучше уж так, на свой страх и риск. :)