Since the previous box (4x4 x2) doesn't print quite well on a ToM HBP, designing a smaller box seems a better use of time (than tinkering with curl issues).
This box holds 8 pieces per layer (2x4), stacked 4 pieces high. While still reaching the edge of the platform, the corners of the box stay well inside the evenly heated area and so shouldn't curl.
Since the box is smaller, the text on the lid now isn't surrounded by so much empty space.
I believe the tolerances in this design should be correct now... However, if you want room for a paper board, you should modify the SCAD file and add a few mm inside height.
I've also uploaded a 2-plate piece set; it's just the original 4-plate pieces reorganized to fit better on the HBP. Many thanks to cymon for the original pieces and helping to work through designs!
2011-07-27; Haven't printed anything yet, but the hypothesis is good.
2011-07-28; Printed the lid: no corner curling; adhesion is good!
2011-07-31; Uploaded new files with better tolerances.
2011-08-02; Removed piece plate; use http://www.thingiverse.com/thing:10500 instead.