Shutter in front of lens? The shutter is attached to a ring that slips on the front of a lens. See section 8 of https://galerie-photo.com/baby-bertha-6x9-en.html for an example with discussion and pictures.
Really? The typical lens sits well forward of the focal plane. An FPS sits very close to, um, er, ah, the focal plane. That's where the film is supposed to be. OP, did you mean a roller blind shutter, also called curtain shutter, or a guillotine shutter or a rotary sector shutter?
Hey, thanks for the photos and links xya and Dan Fromm (I went through both links quickly).
Sorry, I was thinking of something like a DIY guillotine shutter mount for the lens.
To people usually just get a correct sized diameter tube with felt and slip it over?