What should I draw with paint

To make an etching the artist first coats the entire printing plate with an acid-resistant substance called a made from beeswax, asphalt, and other material. the artist then draws on the coated plate with an etching needle exposing the metal. next the plate is dipped in the plate is removed, the waxy coating removed, and the plate is cleaned, inked and printed.

Awork in three dimensions which has height, breadth and depth.

Why did david smith burnish the surface of his work cubi xix?