rubbing the building

At the workshop I rubbed the interior of the building onto sanded postcards. Each postcard was a different room/ or wall in the space. I know they need to be sent somewhere- just not sure where- to the owner of that building that was suppose to be gutted in the near future? should they be sent in a sequence? (for example one each week)- maybe I should send them back to the building...does the abstract rubbing need to be grounded in a location (for example, 2nd room, left of auditorium, wall)?

...another postcard idea: send clear cards with a little varnish (glue) in the mail, tracing the marks of the card's journey