WARNING - EXTREMELY RECOMMENDED
Genuinely impressive - representational 3D forms created on plastic and etched by hand. Lots of fantastic examples, but at 1 minute 43 seconds, you will see a convincing 3D cube:
Scratch-holograms can be made upon CD/DVD cases or other soft plastic using a couple of thumbtacks poked through a stick. Or get fancy and use a professional compass and black-painted polycarbonate plates. Or automate the process with a paperclip stuck into a motorized electric eraser, or a CNC mill with a drag-engraving tool.
For lots of hints, see http://amasci.com/amateur/holohint.html Best is to use a good $10 compass, soft plastic that’s slightly greasy, and replace the extremely sharp compass needle with a small finishing nail. Clear plastic works fine, or place some dark paper behind it.
Are these genuine holograms? Abrasion holography or “Chatoyant holograms” employ the same physics as white-light or “rainbow” holograms invented by Benton at MIT. Benton holograms reflect light from a point source, and they do not require any interference pattern. This is why a Rainbow Hologram functions the same under any wavelength of illumination. The fringes of Benton holograms can have any spacing: even spacings much wider than wavelengths of light. Said another way: if the holograms on your credit cards are genuine holograms, then also “Scratch-holograms” must be genuine holograms.
William J Beaty has been doing this for years (as you will see from his Web 1.0 website), and even guides through writing how it all works and make your own.
More info here