While working with cymon on the xiangqi pieces, the idea for a box came about... The top is embossed with the Chinese "xiangqi".
(The box very barely fits on a ToM HBP... 116mm square.)
Thanks to cymon for making a more decorative box top!
(Use http://www.thingiverse.com/thing:10397 instead for something that can be printed easier.)
When printing on a ToM HBP, you'll want to make sure the platform temperature is set to 110 (or higher), as the piece goes right to the edges. You'll also want to close up the windows of the ToM. If you don't do so, you'll likely get corner curling. (Even so, I still got a little corner curling.)
For my bot, I set the print outline in skeinforge to 0.5mm, and immediately peeled it off before the bot started to extrude the actual piece. This lets the bot center itself just right, otherwise the endstops get in the way and cause x/y-axis drift. (The alternative is to calibrate your platform exactly right for an almost maximal print.)
If you're not having luck with printing to the edges, scale down the pieces and tweak the openscad file. (The emboss was generated using my export plugin for Illustrator... http://www.thingiverse.com/thing:9529)
Notes: as uploaded, the pieces are a little loose; you might be able subtract 1-1.5 mm from the interior dimensions. The lid doesn't sit quite well, so the top lip interior may need to be trimmed a little. (OR increase the interior height.)
My hypothesis on the very-corner-curling involves the bolts holding the platform to the xy-axis. Since the bolts are metal-touching-metal, they're probably acting as heat sinks, thus cooling the corners of the HBP. Since the corners are cool, whatever is extruded there obviously is going to cool faster, and so curl.