A small notebook that uses the discbound system (Discbound/Circa/TUL/Arc Junior 8 discs)

The covers are customizable (blank). The ring discs are smaller than the orginial but still fit the discbound system. 

Print the covers in the orientation shown so that the rough top layer is on the outside of the notebook (but you can also iron the top layer in your slicer settings if you prefer). If you have a textured print bed, then flip the back cover over 180 degrees.