I strongly recommend you visit Mike Lynch's always-worthwhile blog for the link to an intriguing video from the early 1950s showing Milton Caniff in his studio. The material was retrieved by one Jeff Quitney from the Prelinger Archives, a treasure trove of rare films.
Obviously this is raw footage for a short subject about Caniff. It's no documentary. Caniff's 1940s Terry work is mushed together with then-current Steve Canyon drawings. The story is told in the cornball style of humor segments from old newsreels. Caniff calls upon his acting chops for hammy scenes at the drawing board and a truly weird sequence in which he imagines he sees the real-life Flip Corkin reflected in a table top. Most of the drawing Caniff does is inking pinups of Steve Canyon babes (though at one point he's shown adding extra strokes to an already-finished daily). One corny but amusing bit has Caniff measuring a woman's décolleté with a ruler marked to show acceptable amounts of plunge.
At one point the camera pans Caniff's reference sketches of Chinese subjects. Stylistically they look like they came from the Terry years. They're far and away the best art in the film.
If you're a Caniff fan, don't miss this fascinating video.