Old time machinists used to keep lumps of camphor inside their closed tool boxes. I did that too,while I could still get camphor at the drug store. Drugstores USED to sell several useful items that are no longer carried. You can get them on Ebay,though. Keep your camphor wrapped up tight in Saran wrap before you use it. It will evaporate away otherwise. Takes a long time,but keep it wrapped. Unwrap it when you put it into your tool box. I now have a heated and cooled shop,so I don't need it now,but in a humid climate it is a useful thing to know.
I also FULLY RECOMMEND you to NEVER use a wool felt inside your tool box. Wool will eat into your steel tools and cause trouble. The best thing to use is cloth made to line silver chests with. It is treated chemically to prevent tarnish and rust.
I almost bought a Civil War Remington pistol that was minty internally,BUT,had been wrapped in woolen socks for a very long time. The surface of the gun had the weave pattern of the wool socks etched deeply into it.
We used the silver lining cloth to make bags for PGA trophies I used to help make. I lined my gun cabinet with it 20 years ago,and have had no problems with metal rusting that is in contact with it.
Some cloths "off gas". When I made boxes for Queen Elizabeth's gifts when she visited Williamsburg several years ago,I had to get the conservation department to advise me of the cloths that would not damage the silver saffron pot we made for her. Can't recall offhand exactly what I got. It was some type of satin,but i can't recall the blend. Use the silver cloth if you can. A fabric store should be able to order it for you. And,use the camphor. I never had a problem regardless of the type felt as long as I kept camphor lumps in the box.