4 ms·

There's at least one vendor selling calcite crystals on amazon.com for about $15 or so and they say they can be used for this purpose.

• toomanybeersies 9y ago
  You could also buy a circular polarising filter for a camera for $5 that would do the trick: https://www.bhphotovideo.com/c/product/972392-REG/bower_fp67cc_67mm_digital_hd_circular.html https://www.bhphotovideo.com/c/product/972392-REG/bower_fp67...
  • barking 9y ago
    that's a good idea
    • tk75x 9y ago
      Or go see a 3D movie and take the glasses home with you. The lenses are polarized 90 degrees in relation to each other. Pop the plastic lenses out and experiment by overlaying the two pieces then rotating one while keeping the other still.