I know; there are dozens of homemade threaded knobs. Besides, commercial items are widely available in several sizes, shapes, and prices. Furthermore, now it is possible to make them, in any shape, color, and size, at a reasonable price, with 3-D printers.
The threaded knobs I show here are made with discarded plumber pieces:
1. Female knobs. A nut from a flexible toilet hose, a wooden plug, and a type D insert (1/4" x 20):
2. Male Knob. Two matching bronze plumber pieces, a ¼" x 20 round head screw:
3. Male/female knob. Two matching bronze plumber pieces, a type D insert (1/4" x 20), and (optional for the male knob) a ¼" x 20 hex bolt: