My wife really likes the bathroom doors, but was quick and clear to state that she didn't want light coming through the bedroom door! Oh. I was literally back at the drawing board.
So I worked up an idea I had been thinking about as a variation on glass doors. Using 3mm (1/8") thick birch plywood with the traditional zinc channels (called "cames" in the stained glass industry) used for leaded glass, I could make a panel to insert into the door that was opaque and had many options for design. The final design included copper and zinc cames along with an opaque black glass with the stained and varnished wood.