This is an extension on the wonderful Hexagonal shelves made by RiverRaid. The actual shelf can be downloaded as a print in place or in parts:
Print in place: https://www.printables.com/model/61814-wall-mounted-foldable-modular-hexagon-shelf-print-
In pieces: https://www.printables.com/model/59978-wall-mounted-modular-hexagon-shelf
There are four files. For the Serotonin shelf, you will need Hexagon_Extension.stl, Pentagon.stl, and Pentagon_Extension.stl. For the Dopamine shelf, you will need Hexagon_Extension.stl x2 and Hexagon_Extension_2.stl.
The author remixed this model.