I store my 7018 rods in a PVC pipe, sealed at one end and a screw cap on the other end. I place a packet of "Dry-Pak" desiccant in the bottom of PVC pipe as well as in the top. Seems to work well.
I get these packets from my work place, we throw them away by the dozen, weekly.
The packets measure 3-1/2 * 4-1/2 in size and contain about 3-4 oz perhaps???
Anybody need any?