Dunno how they're made, but I'd shell out the $125 and move on with other more important things.
https://forum.ih8mud.com/threads/bug-catcher-wing-window-knobs.1205175/
I think someone is already making the bug catcher knobs for a reasonable price, that project may not be worth your efforts? I lust after your '64 patina 40, I keep coming back here hoping its gone so I can start lusting after something else. It's a good thing there is as much distance between...