There were various fit 9x12 Pack film holder, they must have been introduced in the 1920's (Perhaps earlier) as the 1930 adverts for Patent Etui's mention they take plates, film packs and roll-film holders.

The holders themselves are very simple, similar to 5x4 film pack holders, there's a couple of patents that show how the packs themselves work, I have a PDF somewhere. Unfortunately no company has made film packs for quite a number of years.

Ian