Add a volume layer around an existing volume

I have a 3D box volume and I want to add a layer around it, like a rim but rectangular and parallel to the existing sides of the box. How can I do that in Trelis? Top and bottom surface of the enlarged box can be at the same z values as in the original box.

Thank you

You can create a bounding box around the original volume and then subtract the original volume from the bounding box. Use the ‘keep’ option to keep the original volumes. Lastly, delete the bounding box and you are left with the original volume and a larger hollow volume.

brick x 10
create brick bounding box vol 1 extended absolute 1
subtract vol 1 from vol 2 keep
delete vol 2