The Workbench is the standard mdeling environment of Catacomb 2. In previous versions, you would ask for a new object and then get a new window suitable for modifying it. Now, almost everything is created on the workbench. Collections of components can then be assigned to compound objects using the CaptureBoxes.
The WorkbenchEditor summarises the behaviour of the standard user interface. More introductory material can be found in the overview and there are a number of examples showing how it can be used in a range of different contexts.