The Ladyada Mintyboost design (v1-2) uses something called a boost converter to "boost" the 3 volts you can get off a pair of AA's, up to the 5v required to charge a usb device. Her kit is a boost converter of her own design, and comes with a pcb and components that you need to solder together. An attractive kit, and the v2 kit can source 400ma for faster charging. Her kit, shipped to my house in PA, runs about $23.25.
However, if you're cheap, lazy, or know all about boost converters already and don't care to solder a pcb, there is another solution! Sparkfun sells a pre-assembled 5v boost converter, with a AA holder already attached. Hooray!
So, with a pre-assembled boost converter, our parts list shrinks immensely, as you might imagine. Conveniently, we can buy all the electronics components at Sparkfun. Components
5v Boost Converter http://www.sparkfun.com/commerce/product_info.php?products_id=8249
USB Type A Female Connecter http://www.sparkfun.com/commerce/product_info.php?products_id=9011Total Price with Shipping:
Alright! We saved over 7 bucks, or ~ %30! You'll also need an Altoids tin of some sort. I used a cool round one, mainly because I had it already, and I could wrap the charge cord around it. You can use whatever will hold the components.Tools
1. Soldering iron- Basic one is fine, just for soldering pins.
3. Drill/ Hammer/ Knife/ Hole Punch- To start the hole for the USB connector
4. File- To shapes and smooth off the edges of that hole.
4. Glue gun/ Double Sided Foam Tape- For insulation and holding things down.**Must Read Stuff**
Boost Converter Background http://en.wikipedia.org/wiki/Boost_converter
Ladyada Mintyboost design process (Very Interesting)- http://www.ladyada.net/make/mintyboost/process.html