I was considering making these available through crowd funding, but I'm not sure if I can reach a compelling price point, so I am releasing the design open source. Links to get the boards from OSH Park and the design files at Upverter are provided below.
On each of the boards I tried to use the space to provide additional features to complement the platform they were designed to fit. For most platforms, this meant including a microSD connector, but I went above and beyond for the Itsy Qwiicky. Not only did I include a microSD connector, but I was also able to include a battery connector and charger. All of this and with castellated pins that fit neatly as a little backpack behind the Itsy Bitsy with or without the header pins installed.