Are they eggs? Or balls? Doesn’t really matter. They can hold chocolate.
See here for video: https://youtu.be/CviiN9vELjQ
Files are provided in “snug” and “loose” versions. The “loose” versions slip together easily and can be opened by little fingers. The “snug” versions stay in place better but require as bit more force to open.
The best way to print these is as oriented, with the model raised off the build plate 3mm and tree supports underneath. You will likely need to smooth the surfaces. If they are too tight, snapping them together and apart a few times will loosen it up.
Colour the lines with a marker or oil-based paint pen.
Download the full set: Basketball: https://thangs.com/mythangs/file/796742 Tennis Ball: https://thangs.com/mythangs/file/796748 Baseball: https://thangs.com/mythangs/file/796753