I had a hard time customizing the box, so I took most of the ideas and rewrote the OpenSCAD code from scratch. (And learned a lot about the limitations and undocumented parts of the language...)

The holes are now defined inside a list, so you don't have to define them twice. There's still some features missing from the original.

Determine the size of your package, and where the holes need to be.

Modify the scad file.

• Change the INNER_{LENGTH,WIDTH,HEIGHT} and TOP_HEIGHT variables to define the inner dimensions, and where the top/bottom split is.
• Change the WALL_THICKNESS, LIP_HEIGHT, CORNER_RADIUS, CURVE_SIDES variables to tweak the box thickness, the fit, and how curvy (or not) the sides are.
• Define the holes (rounded rectangle or cylinder/cone) using a list.
• Holes can be partway through. [2011-07-14]
• Define posts (filled or hollow). [2011-07-14]

If the box is too big, you can generate just the top or bottom (GENERATE_{TOP,BOTTOM} variables), or have it render with both halves put together (STACK_HALVES variable).