I have my paints in three different locations and finding the right paint has been inconvenient. I mostly use AK, Vallejo and Ammo Atom acrylics, which come in 17ml bottles. Looking online, I found several vertical paint racks that could hold the bottles but nothing that could hold over 80 bottles - I already had one of those.
So I sat down and designed a 3D printed rotating paint rack that's expandable and can hold 144 bottles (plus several in the lid). This is a "minimum effort" design and print. I printed it in draft mode and yet each piece took between 2 - 4 hours to print. The rack is printed in PLA, although PETG would have been a better choice - but PLA was what I had loaded. All the parts click together and hold pretty well. If I need more storage, I can print another set, remove the current top and click the new layer on:

With all that empty interior space, I designed one side to be a door. The screw in the bottom has been replaced - it bolts a lazy susan/turntable. Each paint cell is 25mm on each side, with a wall at the back to keep the paint bottles from falling in. The smaller hole is just big enough to grab onto the Vallejo and AK 3rd Gen paint bottle caps.
You can see a couple of my old paint racks in the background:

Almost completely full. It clears up some space on my work desk and the paints are within reach:

If anyone needs the STL files, let me know.