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 the mod54 holder, but the measurements are adapted to the smaller 9x12 cm sheets.
There are two ways to use my design:
Either with the original 1 inch tube from your development tank, but without my fittings.
Or without the original 1 inch tube, but with my fittings.
You will need:
1x base tube
2x sheet holder
1 fittings or the original 1 inch tube
If you have a larger development tank (capable for more than 3 35mm reels) you can simply adapt the fittings.
with an even larger development tank (5 or more 35mm reels possible) you could also think about stacking two of my holders...
*** I only have a "Paterson System 4 Multi-Reel 3 Tank" but as long as your development tank uses a 1 inch tube as center and can take at least 2 rollfilms or 3 35mm films at once, you should be able to make my design work.
IIRC JOBO, Paterson and AP are using 1 inch tubes to put the reels on it...
Meanwhile I successfully tested my filmholder with 6 sheets of 9x12 film under real conditions.
ABS recommended because of better resistance to developer chemicals
I had problems with warping when printing ABS so I had to use the following settings to make it work on my printer:
heatbed temp 105° C
printing temp 235° C
print cooling fan off
Use a small file or sandpaper to round the edges.
The design should work without glueing the pieces together, but if you feel more comfortable and know that your glue doesn't react with your development chemicals, you can glue it together :-)