You can use some CopyShape shapes to create drawings with smooth edges.
Joint is useful when you have to join two blocs of different size.
Angle is useful when you have to join two blocs of different orientation.

Fig 2. a.Rectangle ; b.Joint ; c.Angle

Fig 3. a.Rectangle ; b.Joint ; c.Rounded rectangle
The spirangular shape can produce strange moire figure. You could find them useful in decoration patterns.
Moire Example 1 with values
Moire Example 2 with values
Moire Example 3 with values
Moire Example 4
Moire Example 5
Moire Example 6