This is for a 3D digital file of the small watercolor palette in STL format.
Approximate size of the Sakura case is 11.7cm x 9.4cm x 2.3 cm (4-5/8" x 3-1/2" 7/8")

With this digital file, you can have a 3D physical part of the palette printed on a 3D printer. 3D printers are becoming more popular than ever. Have a look around the internet and local suppliers to see if they can make this part for you.
Note: while I have not used the service myself, I have heard good things about www.makexyz.com from a few people that printed this file.

Tip: Also check your public library too. Many libraries are starting to offer the use of 3D printers for a low cost and sometimes even for free to residents!

This palette fits perfectly inside the small Sakura Koi case and can hold 20 colors and a large open area in the front for a sponge or other other smaller art materials.

The one I have was printed out with a white ABS plastic material and the individual colors were all added from a tube.

This has been my main watercolor kit for the past couple of years and has worked great!