Very accurate sundials with easy adjustments for longitude and latitude. These are much prettier than the "World's Most Accurate" sundials, and much cheaper than the "Precision Sundials".
dead link: http://atensundials.com/
Makers of 3-D metal 'printers' such as the one used by Bathsheba Grossman (mentioned elsewhere on QZ Redux).
dead link: http://www.prometal.com/
Make your own "paper" with Liquid Light emulsion, brush it on any surface, then use that like black and white paper. Plus other photo development fun stuff.
I found this site looking for information about magic lantern optics. Besides having a page devoted to that topic, it has a fair sized gallery of slide images, information about various types of lantern, slide restoration tips, resources and links, etc.
dead link: http://www.magiclantern14.btinternet.co.uk/contents.htm
qz thoughts