Most high quality automotive paint shops use large bags of clay pelllet desicant. You can get them for free, and open them and bake the pellets at 200 for about 4 hours. Cool in the oven and repack into the bag and hold closed with a metal office clip.
My AR only STURDY safe is at 18 percent humidity, and has been for months.

Where are you saying to get them for free? At the paint show when they are throwing them out?
Most auto paint shops have big air dryers strapped to the side of their paint booth. Chances are they have a pile of old desicant bags stacked up, or toss them instantly. Tell them your interested and I bet you could get one or more for free.
I always find that showing up with a box of fresh donuts can help getting junk that suddenly becomes valuable the minute someone asks about taking it.
Originally Posted By regalrocket:
Doughnuts can fix just about anything,
This only works with males, females do not respect the doughnut.
Starbucks works on them.