This is a modular system of paint bottle storage designed around the Vallejo range.

The system is built up from 1U racks which each hold 4 standard Vallejo bottles. In front of each bottle is a space for 2 swatches. The idea here is to paint a test swatch from each bottle on both a white and a black undercoat / background to allow for easy colour selection when painting miniatures and other models. If you have a printer with an AMS, you can of course “paint” one of the swatches in black to somewhat bypass the undercoat stage. Units do have a hanging point should you wish to hang from a wall. 

Update A slightly wider rack with 31.5mm holes has been added to this model to fit Monument Paints

Units are joined together with three 4x20mm plastic splines. These could be replaced with wooden dowels or a long M4 threaded rod if desired.  Print the joining pegs with support and you should find that they are a friction fit in the holes.

My painting space is L-shaped. I therefore made a 90 degree corner block to hold brushes and similar tools.  This is symmetrical so can be used at either end.

I'm right handed and like my airbrush close at hand. I therefore made a block to support my air brush, some accessories like spare needles, and thinners to fit on the end of the right hand rack. Simply mirroring this block will probably not be sufficient if you wanted the airbrush at the left hand side.  You will need to edit the FreeCad file to make it left handed.

Update A thin end panel for the left hand end of the system has been added to this set following a request. Mirror this in the slicer if you want to use it on a right hand end.