Twibright Optar

(2007) Previously on HN [2] (86 points, 2 year ago, 38 comments), smaller [1] (14 points, 4 years ago, 3 comments), first submitted in 2010[0]

[0]: https://news.ycombinator.com/item?id=1662657 [1]: https://news.ycombinator.com/item?id=24369534 [2]: https://news.ycombinator.com/item?id=30820836

Also note https://nanorosetta.com/ , 80,000 pages of data on a 2cm disc.