9x12 sheet film holder for development tanks

So you have a 9x12 camera and want to develop your 9x12 sheet films at home in your AP, Paterson or JOBO development tank?
Well, chances are high that you already stumbled upon the mod54 sheet film holder which works really very well for 4x5 inch sheet films (so, credits to the maker of the mod54 holder).
But it is not recommended for 9x12 cm sheet film because of the smaller format having not enough tension to stay in place.
Therefor I just created a film holder which is heavily inspired by