I got the right template from this great inspirations blog. My measurement is as below. It is a flexible measurement that suits your needs.
Bottom pencil box template
Cover pencil box template
It has simple creation and useful for kids. My son has plenty of coloring pencils, from wooden type, crayon type, water color type, pencils and drawing pens. He stores them spread and mix match in mess. In order not to waste costs for buying many pencil cases, I intend to make it few pieces from thick recycle paper or card box.
Here is one of the pencil box designs.
Get it done Upper casing
Get it done Lower casing
Now I managed to organized them well and happy to use own doings.