Ferrofluid is a magnetic fluid which can be manipulated using a magnet.


Aluminum Foil Eagle Sculptures

Sarah Thibault is a San Francisco based artist. While doing mostly painting recently she has ventured out in to making sculpture. She showed several of these aluminum foil eagles her her recent MFA show. The foil birds are built on wire armatures and painted with spray paint. You can see her work here.

Compound Parabolic Solar Cooker

Just the thought of experimenting with aluminum foil sent me searching for solar cooker designs. A solar cooker is essentially a reflective dish used to focus sunlight to cook food. Commercially they come in many different shapes and sizes but with a bit of geometry I think we can optimize a DIY shape for the best light collection. My first instinct was to use a parabolic reflector. A circular paraboloid can collect a large field of light and redirect it  in to a focal point. This allows for far higher temperatures at the focal point than at any other point in the field.

The only problem with this shape of cooker is that it must be positioned to directly face the sun for optimal temperature. Theoretically the solar panel amplification dish design below could be used to create a solar cooker that would collect light even as the sun moved over time.

(via fossil freedom)

There are is a great how to for a compound parabolic solar cooker on instructables. For a simpler rectangular design that can be made with a cardboard box.