scratch hologram - SERP Analysis

https://www.youtube.com/watch?v=0uko9oixijg&pp=0gcJCdgAo7VqN5tD

https://www.instructables.com/The-Scribe-bot-a-Machine-to-Create-Scratch-Hologra/

http://amasci.com/amateur/holo1.html

https://www.youtube.com/playlist?list=PL60100E8F3572CEB1

https://github.com/rdeits/ScratchHolograms

https://www.instructables.com/Make-a-Tool-to-Draw-Scratch-Holograms!/

https://www.youtube.com/watch?v=sv-38lwV6vc

http://3dalter.50megs.com/

http://amasci.com/amateur/holohint.html