We just needed some palettes for mixing color pigments and solutions, so I printed them. I provided two versions a small one and a large. The can be connected vertical and/or horizontal to build larger palettes. The small is not only scaled but also modified.

I printed them using PLA as larges boxes tend to bend up when using ABS. Just snap them together - be careful not to break the connections. Sand them before using. You might need to coat them, as the mixed color will be hard to remove if you need this feature... ideas welcome (I think on Sylgard 184 or similar coating - maybe some easier things...). The bottom is slightly curved (ellipsoid) by intention, but you might print with small layer steps and sand to get it properly (not important for the function).