A remix of cudderbup's design over on Thingiverse.
I've uploaded different versions / heights to find the best focus for you scanner.
I'm using the 0.6 mm Version with ANR glass on top of the negatives.
To use it without the ANR glass, a top cover as in cudderbup's version would be needed to get the negatives uncurled.
The example scan is AGFA APX100 scanned on a V550 at 3200 dpi as a JPEG.
EDIT 2024.03.11
I've added an upper part for the holder to hold the negatives flat without the ANR glass.
The author remixed this model.
Cudderbup's model served as a reference with regards to measurements. However, since I couldn't get my negatives into good focus, I've played with different distances from the bed. I've also included more of the film boarder, added bridges to support the film and resized the model to be used with ANR glass for up to six negatives per strip.