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A three-minute Emacs Rocks screencast by Magnar Sveen demonstrating paredit, which edits Lisp code structurally as a tree of s-expressions rather than characters.

A University of Michigan Medicine demonstration of building a cheap DIY air purifier from a box fan and a HEPA or high-MERV filter using hardware-store parts. It explains why this helps against dust, smoke and viruses and ties it to local air quality readings.