When trying to draw a hole inside of a slab, an Information message tells me,
"A slab hole must be placed inside a slab."
"A slab hole with footing must be placed inside a slab."
"The hole must be placed inside the object."
What exactly does this mean?
By definition, a hole in an object such as a slab, must be completely contained within that object. The hole cannot touch the edge of the object, extend past the edge of the object, or be contained by multiple objects.
To draw a slab hole
Select Build> Slab> Slab or Slab with Footing from the menu, then click and drag to draw a rectangular slab.
Click on the slab to select it and edit its size and shape as needed.
Select Build> Slab> Slab Hole or Slab Hole with Footing from the menu, then click and drag to draw a small rectangular hole entirely within the existing slab.
The Create Hole edit tool also allows you to draw a hole inside of a selected slab or slab with footing.
Once drawn, slab holes can be edited much like slabs can. The only restriction is that they must be contained entirely within one individual slab object.
You can see the results in a Camera view.
If you need to create a cutout in the slab's perimeter rather than add a hole to its interior, you can add breaks to its edges.
To add edges to a slab's shape
Click on the slab to select it, then click the Add Break edit button.
Click on an edge of the slab where you would like to add a corner.
When you click, a new diamond-shaped Reshape edit handle is created.
Don't worry about placing the new corner with precision - the shape can be edited accurately later.
Click and drag the square Move Line Segment edit handle to move the edge on either side of the new corner.
The new edge can also be moved using dimensions.
You can also click and drag the Reshape edit handle at the new corner to change its location and the angles of the adjacent edges.