This is a very simple design for easy and quick onigiri making. Just shovel in the rice, press it down and pull the shell up and voila, there is a nicely shaped onigiri for the bento.
The kids love to play with it and more keen to help with the lunchboxes!
Technical
I used eSun ABS+ to print them but I'd guess any material would do.
Layer height: 0.2
Perimeters: 3
Bottom/top layers: 3
I used a slicer modifyer to make the press part flat surface is 100% fill and the handle is 20%.
The shell took me 1.5hrs and the press is around an hour.