In a previous post I showed how to make a rack trunk box from a plastic 30 caliber ammo can or dry box. To continue on this theme, I put together a rear pannier using a plastic .50 caliber ammo can.
The dry box ammo can is from Cabela’s and measures 14″ long, 8″ tall and 7.5″ wide. It has a hinged lid with a rubber seal. The top handle can be removed (with some effort), or used to help secure bungee cords. There is a padlock hole near the top catch.
I ordered replacement pannier hooks from Detours, known for their line of bicycle luggage. The hooks come with several sizes of snap-in adapters to fit the rack rails and mounting hardware.
I got the shock cord hardware from Seattle Fabrics. Those ends are called shock cord rivet mounts. The shock cord and S-hook came from Seattle Fabrics as well.
The screws that came with the pannier hooks were too long for this application, protruding into the interior, and I feared they would snag on stored items. I used 5mm x 12mm pan head stainless screws and nylock nuts. They are a little short and I will be replacing them with 14-15mm screws and washers.
Installation was a simple matter of spacing the hooks to suit my rack top rail and drilling the the plastic box. When I replace the mounting screws I will be adding a dab of silicone sealer at each hole for a good waterproof seal.
By my calculations the box has a volume of 840 cubic inches or 13.75 liters. It weighs 2 pounds total.
Dale's Journal 
Nice. Thanks for sharing.