I put one of these home-made units in my four cases with the guitars an hygrometers about the first week of December;
I have two guitars in each house and the Dread Jr is in it's gig bag. I just recharged the beads in both houses this week. They were about half sized in the hard cases and very small in the gig bag. Hygrometer readings in the rooms, yesterday upstate 26%, Long Island, today, 25%. Inside all four cases, even the gig bag, are steadily in the low 50's. This is the first time I've had to do anything with these.
They've been effortless to use and it only cost me about $30 for all four of them.