wisedry 2 x 500 Gram See-Through Silica Gel Packets, Color-Indicating Desiccant Packs for Storage, Reusable Gun Safe Dehumidifier, Rechargeable Car Dehumidifier Bag

I use these in my knife drawer with all my fancy japanese kitchen knives. Would work great in a case also. And you can recharge/dry them out once they soak uo all the moisture they can manage