I found a mamiya rb67 finder that didn't have the logo part that retains the finder to the camera, so I 3d printed it. It uses 2 M2 screws (I think the ones I used were M2x3) and they are screwed through the retaining bar, the finder, and into the logo piece. It then locks by sliding left to right.
I printed mine at 0.15mm layer height with enough perimeters to be solid. Hole diameter is 1.9mm which allows for some bite from the screws but I wouldn't attempt to pick up the camera by the finder or anything.
The author marked this model as their own original creation.