Project Ara Module Developers Kit

With the firs dev conference just days away and rumors suggesting prototype hardware might be fully functional within a matter of weeks. Today Google releases the Module Developers Kit that hardware guys can use to start crafting their own interchangeable elements that will make up the final Ara phones.
The kit covers design guidelines, describing valid module dimensions, internal construction, and layout for power/communication pads.
It has some pretty cool features like how those electropermanent magnets are switched on and off to hold modules in place.