Shell for a Pentax D-LI90 based USB charger. The D-Li90 is used by the Pentax K-7, K-5 and K-01.
I use it to keep my phone (which I use as a gps) charged while backpacking. The nice thing about this is a 'dead' battery that won't work in my camera still has plenty of charge to keep my phone topped off.

Instructions

Requires a usb connector, a voltage regulator, and some wire to assemble. I used a Dimension Engineering DE-SW050 (http://www.dimensionengineering.com/products/de-sw050)
Loop the wire through the holes in the part to make contact with the battery. The two parts press-fit together.