This is a stackable shelf module, 190mm wide, designed to fit standard 25mm diameter dropper bottles such as those used by Vallejo or AK Interactive.
https://www.thingiverse.com/thing:6006265It is not a complete one-step shelving solution. The modules will need to be glued together, and the whole set will need to be secured to a base-plate of some kind to keep it from tipping over. Depending on the number of layers, some support for the rearmost shelves may also be necessary.
I've included bottom and top shelf STLs — they're not strictly necessary, but they make a more compact unit.
I've also included STLs for some bracing pillars for the back shelves, in heights to fit one, two or three levels. If a higher brace is required, two of the shorter ones can be glued together.