The "Spotter" is a small ornithopter that circles or hovers over a working spice harvester watching for "worm sign", the tell tale approach of one of the giant native sand worms that can easily lay waste to an entire harvester in moments.
While mentioned in the movie by both Dr Kynes (In a delete scene) and by Duke Leto (during the rescue of the spice harvester workers), the "spotters" are not seen on screen.
I've created several designs & models for the spotters so far but have been unhappy with all of them - as they really didn't match the design aesthetic of the film -
Found an image of a model on a website that while different from the main ornithopter seen in the movie, to Me seemed just right - that combination of similar but different enough.
So I modeled it up to match the design of My regular "Special Edition" ornithopter" and I am quite happy with how it came out so far. (Though My hypervoxel dust cloud is really lame!)