Hi rdeutsch,
Andy is right, of course: he's probably the only one in the world who knows everything about AC3D. But as such he sometimes tends to forget that things aren't always as easy as they look to him
Try the following:
once you have your frame with your polygons in it:
- toggle to 'vertex' mode
- select all vertices, including those of the main frame
- go to 'vertex' menu and click "Create 2D Mesh"
Caution now: the complex mesh you see is a NEW object that overlaps your previous frame and polygons - move it aside in order to avoid getting confused.
- toggle to 'surface' mode
- in the new objects identify the surfaces corresponding to the polygonal holes you want in your frame, select them and delete them.
Et voila, erledigt. Viel Glück.