It would not take much for a
coin flip box but there's no limit on what you could use. It can even be ingested without harm though I wouldn't recommend it ( I am a pediatrician in real life and get frequent calls from parents whose kids ingested the things). Packets like come in electronics should be about the right size so the size you mention is probably about right. They should be changed periodically based on the humidity of the storage location. Unless they get submerged in water I doubt they will feel moist. You can actually "recharge" the packets by exposing them to about 150 degrees F for about 1/2 hour.
I also collect antique guns and keep a container in my gun safe--I just have it in a
pan in the bottom. About twice a year I'll put the
pan in the oven on low setting which is about right. So far no rust on my guns which are stored in a basement in Alabama, one of the most humid states.
By the way, I keep my coins in the same basement without dessicant and have never
had any problems with
bronze diseaseCharles M.
