"Make one?" for a flat tactile switch.
Go to McMaster-Carr and purchase two sheets of rubber. A thick one for the button and a thin one for the support backing. Cut a small square out of the thin sheet. With a paped punch, punch a small "button" out of the thick sheet. With rubber cement(?), super glue(?), Barge cement(?), something appropriate for the material ... glue the button in the center of the small square.
Vwa La!...Rubber button cap!
Just something that the mind comes up with at 4AM.
Ken