There is no need to explode - just don't create two groups. Change this: bbx1 = Sketchup.active_model.entities.add_group g1 = bbx1.entities.add_group face1 = g1.entities.add_face boxpts face1.reverse! face1.pushpull(bbxmax.z-bbxmin.z ) to bbx1 = Sketchup.active_model.entities.add_group face1 = bbx1.entities.add_face boxpts face1.reverse! face1.pushpull(bbxmax.z-bbxmin.z ) If you read your code carefully you will see that you call add_group twice, once in the root entities element and once in the first group you created.