On a semi serious note, this is precisely how most 3D printers work.
Many use wax as a production material.
I once saw one loaded with a starch based substance, and it could print a reasonable looking (and just about edible) pizza base.
Wouldn't it be simpler to use a device more like a scanner, (upside down and sans glass) with a row of closely spaced jets across the head?
You could heat the whole head arrangement up, and apply pressure to a reservoir of melted emulsion to spray it out.
Then, if you varied the speed of the head, you could adjust the coating thickness.