I spent a few minutes last week finishing up the Tidalforce Electric Bike Bottle Mount Battery Pack.
I wrapped the case with an acrylic outer shell and overwrapped it with some very wide gaffers tape. It looks very clean and matches the frame of the Tidalforce bike very well. It's highly water resistant and the acrylic protects the cells inside.
With the battery mounted near the middle of the bike, the balance is greatly improved over a rear rack mounted pack. Also, the bike feels so much lighter to move around. I haven't measured it yet, but it has to be at least 25 lbs lighter than with the front hub battery.