... create a cylinder or a cone?

You'll want to look at the classes PolygonDisk and PolygonCone, which are included in the file Shape.tz. By giving a PolygonDisk or Cone a large number of sides, it will take on a circular form.

Some sample code:


disk = new PolygonDisk.
disk init-with radius 1.0 sides 30 height 3.0.