Case for a voltmeter/ammeter circuit case, used for measuring the output of a solar panel or other device. A switch on the back switches the display between voltage and current display. An alternate version using a different circuit can be found at http://www.thingiverse.com/thing:302595
Uses a voltmeter/ammeter circuit and a 5.5mm x 2.1mm or 5.5mm x 2.5mm jack.
Some of the parts used for the meter: