Location: 13 Special Construction
A big dull block for subtracting a rectangular hole into a ceiling slab. Why not use a slab for an operator? Why not just draw a conventional hole in the slab? Because while the 3D block is dull, the plan symbol is rather clever, responding intelligently to the new ceiling switch in Model View Options.
To review what the ceiling switch is all about, check the Ceiling Line JM11 post. Like that line object, the soffit cutter has separate attribute settings for plan and RCP. Either set of attributes can match the objects settings, while the other can differ. I like to treat the plan as primary and the RCP as the variation, so I have the object's linetype set to 'Dense Dashed'. In the parameter list, the Plan Linetype is 0 (matches the object settings), and the RCP Linetype is Solid Line. You can also change the pen, but I don't see the need.
The cutting takes place with solid element operations, with the main ceiling as target and this object as operator.
Such an object has peculiar display requirements so the layer is very important. It shows in plan, RCP, and working model/section/elevation (so you can work with it), but is hidden in output sections (where you want to see the effect of the operation but not the operator itself). So in the templates we have a new layer, X Ceiling Cut. Like most cutting layers, it's wireframe. You would need to create this layer in running projects and show/hide/wireframe it as described.
Of course, sadly, for a non-rectangular hole you still need to use a slab, and you still need to trace.