Important: You need to print this adapter with transparent filament!
Print it with 0.2 mm resolution.
Why? Short anwer: Non transparent adapters will result in dark images. The long answer you can find in my blog.
The uploaded design (FreeCAD) is version 2 of this adapter.
Update 2022-04-06: Uploaded version 3 now, improvement is a bigger gap for the film between ground plate and top plate. The film fits in now easier, even if the 2 plates are sticking together. The notch moved 1.75mm to the right.
Since we're “abusing” the 135 mm setting you where the image area is 36x24 mm you will see more than just the APS picture in the scans. That means you have to crop them to the APS area. I use digKam fir this task. At the end you will have your old APS films digitized with 10.8 Megapixel resolution.
The author marked this model as their own original creation.