Newsflash! The photos below show a slide viewer that allows you to view a single slide with both eyes. It might have similar optics to the device in this Instructable. I suggest trying the following:
1. order a slide viewer on e-bay for $10-20.
2. cut the viewer in half along the slot for the slide.
3. cover the eye holes with the red and blue colored filters.
4. put your camera where the slide goes and take a photo.
Please let me know if this works.