IoT Zürich Meetup, @iotzh on Twitter, represented at Maker Faire Rome 2015 by @dr_m_kroll and @tamberg.
Design files on Thingiverse, Code on Github.
Bluetooth 4.0 open source hardware by BlueKitchen and MiKro-Labs.
Details on tamberg.org
Design files on Thingiverse, pictures and video on Flickr, assembly instructions on Instructables.
Design files on Thingiverse.
Details on make.opendata.ch