View-Masters
Freeviewing 2X stereoview images
To view the image in 3D, start at of a distance of 20-24 inches
Focus your eyes at a far distance. Make your eyes merge the 2 images. You will see 3 images with the center image appearing 3 dimensional. Once you are close, the 3 dimensional image will come into view clearly. If the center image is not clear, try to bring some features that stand out together. This will become easier with practice.