Not to muddy the water but.....

On E-bay I saw two interesting items - 2 different people selling the legendary Thorton-Pickard roller blind shutter which does indeed mount on the front of the lens and offers more speed settings than the famous and durable Packard...

And a cleverly adapted shutter curtain from the rear of an older Graphic, Speed or otherwise I'm not sure. The whole device went where the lensboard would normally go, although it would recess behind the board's normal position, and on the front, it was designed to accept a Kodak MV lensboard.

Now, TRYING TO FIND the first and PAYING to get the 2nd BUILT are of course onerous tasks, to say the least. The Packard is definatley the easy and safe way to go - but the other two are really intriguing, to say the least.