This is a Camera Tripod mount adaptor for the 3D printed AstroPi Flight case from the Raspberry Pi Foundation (https://www.raspberrypi.org/learning/3d-printed-astro-pi-flight-case/).
The mount attaches to the AstroPi through the corner bolts but, due to the extra thickness of the arms, you'll need some slightly longer bolts (I'm using 35mm ones). Once installed the AstroPi can be attached to any standard 1/4" tripod mount.
I've included two variants of the mount. The 'threaded' variant has the screw thread as part of the model, requiring no extra parts, but may be a little trickier to print successfully. I've found it a little stiff to attach the first time, but then is easier to attach/remove.
The alternative model is the 'Nut' variant which has a space for inserting a 1/4" UNC nut for bolting to a tripod. This should, in theory, be an easier print, however you will need to source an appropriate nut to finish things off. Hopefully they have a somewhat standard outside dimensions, but for reference the ones I purchased can be found on ebay (http://www.ebay.co.uk/itm/260467071167)
For my printer I used a brim to stop the arms from lifting (Printing onto a heated glass bed)
I printed the 'threaded' variant at 0.1mm, other layer heights may or may not work.