You can use the 9 DoF sensor without an enclosure, but mounting it in an enclosure will give you steadier readings and a better idea of the physical orientation of the sensor. It may be assembled in a 3D printed cube, described below. By default, the cube has mounting holes for a Metro Mini V2. However, there are mounting plates for Metro, Feather and QT Py format boards as well.
The STL files can be downloaded directly here or from Thingiverse.
If you are using a mounting plate, mount the plate to the cube using the Metro Mini's mounting holes with M2.5 screws and nuts.