[TenTec] Homebrew chrome knob inserts?

[Barry N1EU <barry.n1eu@gmail.com>]

Does anyone have a method to create the chrome knob inserts that get glued
to the center of the Corsair II knobs?

Evidently there are NOS knobs available without the inserts and I'm
wondering how to make it match the original knobs with inserts.

Thanks & 73,
Barry N1EU