[Andy]

You can use Vertex->create-convex-surface/object to make objects that have holes in.

e.g. to make a round hole in a box:

1) create a box
2) create a cylinder that extends though the box and comes out of opposite sides
3) select-all (in vertex select mode)
4) Vertex->create-convex-surface/object

Then you can remove the original box and remove the surfaces from the cylinder 'ends'. Finally flatten the vertices on the sides where the holes are (select the vertices at one end and resize to zero)

For more info on this function, see the section in the manual which demostrates making an aircraft fuselage.

Hope this helps,

Andy