Making holograms with a pen plotter

This is "old Internet" style fun territory (along the same lines as the Tom7 fun, if not quite as deep). I felt that the olive oil + fingerprint + phone screen was a really nice way to illustrate the core concept. Especially clever because it used something common and annoying to help describe how the plotter does its thing.

Related, "abrasion holography", with great good success for being hand drawn: http://amasci.com/amateur/holo1.html (1995)

Maybe could swap out the pen for a needle?

Steve Mould has a great video on youtube explaining how they work https://www.youtube.com/watch?v=sv-38lwV6vc