Summary

The Nuva symbols held the power of the Toa Nuva, and also served as the keys to the prison of the Bahrag - the cube being the lock.
Who doesn't love bringing childhoods back?
BIONICLE lives on!

EDIT 27/11: I found that the symbols were way too big, so I had to redesign them, or you guys will have a lot of sanding and filing to do. The symbols have been rescaled, so everything should be fine, since I personally printed them out to check.

Instructions

Well, I took a veery roundabout way to do it...
The cube was simple enough, dividing the thing up into sections then reverse-extruding (subtracting) out of it to create the symbols on the cube. You might see a smaller cube within it, with the symbols a sort of 'cage around it, but really I started with the whole cube before anything.
The symbols were a whole lot harder. Since I was too lazy to do this in AutoCAD (which would have been a helluva LOT easier), I did it in 123D. I started with a sphere, cut off a quarter vertically, and to create the slopes I had to overlap cuboids to subtract off the extra parts (lazy way turned out to be the hard way here). Once that was done, I just mirrored the symbols on the cube over.
Also, when making the cube, please use supports, or bad things will happen to you and your dog......

EDIT 27/11: I printed these on the Makerbot Dual, and for some reason black ABS works much better than, say, white ABS. Something to do with expanding just after extrusion..

BIONICLE Nuva Cube + Symbols