... recent we discussed assembling objects with small 'bricks' or balls.
It's possible to pick small parts from a sort of magazine or feeding conveyr, place them in a glue-reservoir and then place in the target position, so you can build 'lego-like'.
Another idea with metallic parts (or balls) would be placing the part in the right place and then discharge through the part to weld it with the surface.
With small balls this could be a good surface accuracy too, but then you must have a very good supporting/feeding machinery for a perfect uniform and error-free handling and the fabbing-time is much longer then with paste ...
Viktor