Years ago I started using cardboard VCI chips to protect my dies and other small metal parts from corrosion. After I moved to the coast this became even more important because as they say, rust never sleeps. Anyway I recently started using these small 1x3 Zerust Plastabs which unlike the cardboard chips, are good for 2 years and don't absorb oils or dirt. They also market a number of other rust prevention products for firearms such as bags, vapor capsules, barrel inserts etc. Just something to think about if you also live in a humid environment, especially during the summer months.
Blessed are the flexible for they shall not be bent out of shape.