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I carry my G-Tech G-SPEED Q in an Army surplus ammunition case. There are smaller ammo cases but they might still be too large, but if you pad it with foam you'll take up a lot of space. They are strong, watertight, and about $8.

The more ready made alternative is to get a waterproof flight case, like a Pelican case, SKB, or Gator. They are pretty standard injection molded, foam lined cases with rubber gaskets. This is what I would recommend for something easy. It will be a little large, but I don't know what you want or need.

B&H sells a lot of those cases. They might be advertised as flight cases, camera cases, electronics cases, etc.. B&H will have very good prices even on these, but you might be able to order direct, especially helpful if you find the perfect size and no store carries it.

The G-RAID can handle being tossed in your bag. It's very robust, but it might as well damage something else that way.
 
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