Nesting dolls in the shape of eggs (stacking dolls, Matryoshka dolls, Russian tea dolls, Russian dolls)
The eggs consist of two parts that snap together. There are 6 sizes of eggs, the biggest being 10 cm tall. There's also a center egg that is solid and printed in two parts as well. You can scale them up or down if you want.
Disclaimer: You may need to adjust the horizontal expansion in your slicer setting to make the pieces fit together correctly. I've already added a bit of a gap margin in the STL files, but results may vary depending on your printer and filament.