Michael A. Terrell wrote:

Fair Radio used to have some in their catalog, and they were used in
all of the old Delco (and some other brands) car radios of the '60s and
'70s.

Just about all the radios I've seen with mechanical pushbuttons for
station presets used permeability tuned inductors -- the pushbuttons
each just positioned a ferrite core to a preset depth in a coil. It
wouldn't be difficult to construct one, unless you're mechanically
declined like I am.

Roy Lewallen, W7EL