I'm going to try to fit this in an Adafruit Altoids Gum tin, so it needs to be compact. I'm making a 3D CAD model in SketchUp to make sure it all fits:

That battery is the SparkFun 1000 mAh one; it's the only one from either store that fits in the case according to my model. Left to add: the display (4-digit 14-segment white LED), the battery backpack, the buttons, the probe connector, etc. Except the display, they're all pretty small, so I don't think they'll be hard to fit in.