Raspberry Pi Zero v1.3 simple case

I wanted to make some changes to the Pi Zero case and lid by [red9987](http://www.thingiverse.com/thing:1589023) and [cfunseth](http://www.thingiverse.com/thing:1227867). I re-created the design in 123D Design and made some small changes. The first is a power logo on the lid, to indicate which of the two micro-USB ports was for power, since I could never keep them straight. I also added a hole over the LED to help see the power/activity indicator. There's also a notch on the back of each cover to help open the case later. The last change was to add a block to each cover to help hold down the board inside the case when assembled. Without the block the Pi Zero kept moving around with the weight of the mini-HDMI adapter attached to it.

I added a case top with a cut-out zero logo to help with air flow for anyone that runs an overclocked board but doesn't want the gap for the IO headers.

I would suggest printing the case bottom at 100% infill, or adjust your shells to make sure the w