I store my packs in a small steel toolbox. It allows for ventilation out the lid should the unthinkable happen. I use some thin foam adhesive tape on the bottom of the box to provide some padding. A picture is attached. They only cost about $10. Some people use ammunition boxes too.

Check the rating of a LiPo sack. I think you'll find them next to useless for a 10S pack. It's a false sense of security IMHO. I do however use LiPo sacks for my little 2S receiver packs and then put them into the steel toolbox.

Cheers,
Jason.