AutoCAD produces exquisite 3D bird cages

The following is a completed rendering.

First make the bottom of the cage!

As shown in the picture, draw two concentric circles, the size is custom!

Using Cut (TR) command, the second outer circle cut line, as shown!

and then drawing command (the EXT), the two circles are stretched, after stretching, for a difference set operation, the outer circle Save!

UCS changed as the coordinate axes, XY plane perpendicular line, as shown in FIG do circle, the radius of the circle can be customized!

then continued with round copy COPY, the center of each endpoint (copy, I copy only half, the other side, mirroring command can be used to complete)! FIG:

again using EXT command, selecting a path stretching (COPY path just inside the circle), the bits are each circle extending!

after stretching is good, three-dimensional image (MIRROR3D) to get the other half! The central axis is the red round bar in the picture, and the mirror surface is the YZ surface!

FIG transition axis (the UCS), a two-dimensional line, arc commands, shown in FIG line (which identify the center line (red))!

use PEDIT command, just the cage frame line by line arcs composed polyline, so that we may be stretched!