After purchasing a nifty metal dice set on Amazon I read in some of the reviews that it would be best to store them in a partitioned container to prevent the heavy dice from bumping together and causing dents/scratches.
I changed the shape from 12-sided to round, increased the size of each chamber by an eighth of an inch, and reduced the clearance between the dice and the top of the container.
I also included a version with a dragon design inset on the top. It isn't my design, as it was generated from an image I found on a Bing image search, but it originates from this article:
It's apparently the logo for Dragon army from Ender's game, but I just selected it because it looks cool.
I consider this design to be mostly complete. One warning if you print the dragon-emblem version: use supports, and be very careful when removing them. The bottom of the inset design is VERY thin so you may inadvertently punch a hole in it if you aren't careful.