Okay, I replaced the packing peanuts with hard styrofoam and it is much better. I'm still not happy with the edges, but that would be too hard to get right.
I think if I wanted, I could fit about 4 of the 6 (AAAA) batteries back inside and have the battery actually work. Some other time if I get really bored, I might get a rechargeable 9v and do that.