Looking through Thingiverse you will find lots of Micro:bit battery holders, however, none quite matched our needs. We wanted a robust holder that could be worn on a lanyard, worked with Micro:bit v1 and v2 and gave access to the rear power button. So, inspired by the best bits of our favourite designs, we decided to create our own. The result is the "Thingmy", a 3D-printable Micro:bit battery holder that can be used as the handheld "controller" part of a Micro:bit artThngs art installation as well as being a general Micro:bit holder for use in workshops.  Feel free to download the STL file from TinkerCAD, modify and share it. Some modifications are planned for the future, such as making it possible to put the Micro:bit snuggly in place forwards or backwards (to expose the edge connector) and better battery cable management. We are also experimenting with a lighter "clip" version.