This is a mix of the original idea from Pyroguy096 at https://www.printables.com/model/143412-stormlight-book-end

with different dimensions and the 3D-Logo of the Knights Radiant from banta124 at

https://www.thingiverse.com/thing:3292921 .

There is also a blank side available, both short sides are 96mm long so don't worry about which side it is.

Use super glue or something alike to fix the side in the grove of the stand.