The cloud chamber may no longer the particle detector of choice (that would be the bubble chamber) but easy to build yourself (in modern or vintage style) and watch cosmic rays in the comfort of your own home.
Instructables for showing what you make and how to make it. Not just any DIY site, the creator Saul Griffith has an impressive pedigree. The site comes with all the things you'd expect from a new collaborative widget including Creative Commons licensing options and of course tags. From the about page: "We like to think about the physical world as something that is programmable. We like to think of objects or stuff you make as 'code'. In other words, we are approaching the physical world as something that is describable and replicable." Dive in and learn how to make a pimped out megaphone helmet, Hungarian bookshelves or canned applesauce. (via)