If you ever need a shelf or a library right away, this is just for you!
You can DIY your own with this Joints and some boards
What you build depends only on you, you can copy the examples above or invent whatever!
Joints must be fitted with wooden boards. For the wood I base on the standard measure 18.5 mm.
You can screw it to the wall if necessary. Check the panels I uploaded with the images for further info.
Pd, settings = ABS
1) Basic sketches in notebook
2) 3D modeling in Solidworks
3) Test print