so, mark confirmed that there is a practical ball droid - but is it practical in that shot in the teaser? Kind of like how they have a 'hero' version of props but then make a whole bunch of replicas for different action sequences and shots.
its funny, when i first heard confirmation that there is at least 1 practical model made of the droid, it reminded me of when i first heard that kenny baker was only in the very last scene in AOTC :(