I found some great little utility cases recently. They are made by MTM Case-Gard for ammunition storage. Rated to carry 85 lbs, with a rubber O-ring seal. Two sizes 19x16x8 and 19x16x5. Best of all $20 each on Amazon. I included a BEC box in the photo for size reference. I have no financial interest in the company or Amazon.
Just wanted to share.