Okay, bought a nifty mechanical pencil and an assortment of leads:

and while the pencil fits neatly in a slot in my bag, mislike the pencil lead boxes rattling around loose (and worry about breakage or loosing them), so we need to make a box.

Fortunately, the lead cases are shaped so that they nest efficiently:

so we just need a box with a single pocket which is: ~7.25mm deep, ~56.5mm at its widest and ~76.75mm tall (probably we’ll swap those two numbers)

We have some bamboo flooring stock (this is wonderfully convenient for small projects — just buy some samples at a big box store), so we’ll use that.

First, we load up our OpenSCAD program…