This part can take up 36x24mm slides for scanning them with a DSLR camera. You can either catch daylight or use an iPhone 6 to project homogenous light from the backside of the slide.
The problem with making photographs from old transparency slides is to ensure homogenous lighting.
My idea was, to use an iPhone 6 showing a white screen (e.g. using the App
LightTable) as a background illumination.
See how to build your own DSLR slide scanner on my page:
https://www.michaelstapfer.com/single-post/2017/03/06/DIY-Transparency-Slide-Scanner-with-3D-Printed-iPhone6-Projector