YASS (Yet Another Shelving System), customizable

thingiverse

A Simple, Parametric Shelving Bracket and Triangular Gusset System. There are only 2 adjustable parameters in the *.scad file: width (the exact width of your planks) and hole (the precise diameter of the holes designed specifically for screws). For any standard bookshelf, you will need 2 sturdy uprights and a specific number of horizontals. These are usually cut from one single width of plank. You'll require 2 brackets per horizontal and at least 2 gussets are highly recommended. For instance, a 4-shelf unit like mine demands 8 brackets and 2 gussets. The brackets bear very little weight, as the top screws, inserted from outside, carry the actual shelf itself. The brackets mainly serve as a drilling guide and a step to mount on securely.