Here are some links to popular YouTubes on how to pick up the image from a surface relief hologram, and my critiques of them. (Don't forget, a critique is about the work, not to be taken personally!)  Ann Reardon, charming English accent, looks like she gets decent results, but please spare me the lame attempt at explaining defraction.  (It's spelled diffraction for starters!)   Action Lab  Info at about 6:00  Quantum mechanics, my ass. But otherwise pretty good.  Tech Ingredients  This guy looks familiar, but boy is he so verbose!  I wish these guys would omit this pseudo scientific spiels, it only points out how little they know.  Does go into great detail on how to make the sugar version, starting at about 7:00.  Simply Nailogical  The zaniest couple ever, but they do give us the most successful shot, at about 14:00, using the cheapest chocolate!  Applied Science  Does have a lot of practical tips.  Instructables  Might have to join the Instructables group, but the directions are plain and written and not an annoying video, plus they leave out the pseudo-science!  Here is their pdf.

There's probably more, but I think a successful attempt can be made from the info in these, especially the Instructables.

This is how I do it, borrowing the use of the cheapest chocolate from Simply Nailogical.  First the chocolate eggs are grated.


The grated chips are placed on top of the diffraction grating in a baked enamel darkroom tray. Thick pieces of tape or other spacers on the grating determine the thickness of the final chocolate layer. .

Top Pan

This tray with the grating floats on top of another tray filled with H2O on the kitchen stove. 

2 trays

When the chololate starts to flow the top tray is placed on a counter, a piece of waxed paper placed on top of the chunks, and the softened chocolate is spread out with a roller. 


Then the tray is placed on top of another big tray which has cold H2O in it.

The Cold Tray

When the waxed paper can be lifted off the cooled ooze, the chocolate can be peeled off the grating!


The chocolate layer needs to be at least a couple of millimeters thick to support itself to peel off the grating.

final product

Any chocolate residue can be easily removed with a soak in soap and water.


After drying, the grating can be places in the sun-lit kitchen window to project rainbows onto your refrigerator.

Rainbow reefer

The holographic diffraction gratings I use were made at the Home + Studio of E. Wesly & Sons. They are about 30 by 40 centimeters on a 175 micron polyester film base, and are available by writing to me at eweslystudio at gmail dot com.