Among her many optical illusion artworks, Devorah Sperber creates reproductions of paintings using spools of thread. Like Seurat or Chuck Close, the spools are used in a pointilist or mosaic effect to give the viewer the big picture more clearly the farther away from the work they are. Many of the exhibitions also feature a viewing lens to make the "painting" come into focus a bit more clearly, which is also why they're upside down. This Mona Lisa closeup used 5,184 spools of thread to make, and her Last Supper uses a staggering 20,736 spools! Luckily for the artist, Coats & Clark, one of the world's largest thread manufacturers, partially funds her works.
Found via Extreme Craft.