Summary

I designed this around the Blackwing 602 but should fit others as well.

There is a step inside where the pencil goes. The step is to have the pencil rest on it, so the tip isn't touching the bottom. This is to prevent damage to the tip. There is 30mm of space between the step and the bottom. This should be long enough for pencils sharpened with a 2 step pencil sharpener (1 step needs even less space).

The part above the step is to keep the pencil upright,