The Modular Hood for my Cokin Seris P filter system had broken, so I designed a replacement.
the last photo shows the original (broken) one and the printed replacement.
Replacement clamps on support as original did, by slightly pressing the two flat sides of the hood, widening the other two sides slightly to allow them to slip over the support until the support's pins go into the hood's slots.
This first design does not reproduce the original's ability to stack several hood pieces together to make a longer hood, as I never needed it. If I have the time, I might make a second version that allows stacking.
I suggest printing in PLA, with 0.2mm layers and support turned on to get nice and precise slots.