Graphite dust restbox

Writing with a pencil has the drawback, that this things have to be sharpened from time to time. So I use a "fixpencil" (caran d'ache), which I only have to sharpen the lead. Unfortunately I don't have a trashcan with me all the time.
So, to collect the graphite dust, I created this little Box.

The lid goes in very tough the first time. But it is not intended to take off!

The little "step" inside is to hit the sharpener against it, so the dust "shakes out".