About 20 years ago I bought about a dozen Seeburg 3W1 wall boxes that were in a Sacramento retro 1950s diner that  had closed.  Each of them was mounted on one of these custom made bar or counter brackets.  I recently found this one here in my building.

It is well made of steel and it  has been powder coated.

The last photos show how high the 3W1 sits from the counter top.

Overall length is about 20 inches.