My room sits around 10% humidity in the winter.
This causes all sorts of problems in the instruments, from cracked tops (has happened to at least 3 of my guitars and 2 ukuleles), to a drying out of the glue used to hold the instrument together, which can cause loosening of inner cross bracing and buzzing, and in some cases, loosening of the bridge.
This particular winter has been brutal, with two instruments already cracking, in spite of keeping two whole-house humidifiers running in my room. I started looking into purchasing Damp-It sponges for each instrument...until I found out that the price would be at least $12 a piece.
Considering the fact that I have 30 solid ukuleles, and 32 solid-top guitars in the room (if I choose not to humidify the laminate ukuleles which are not as susceptible to humidity issues), that adds up to a LOT of money that I don't have in my budget.
I have long made DIY humidifiers for my own instruments that sit in their cases (film canisters or medicine bottles with holes in them and a sponge inside), but that solution won't work in this case...I needed something that would hang in the instrument, and finally came up with a solution: Plastic Test-Tubes with water beads! Price difference?
Best case scenario with Damp-It humidifiers would likely be $10/piece X 62: $620.00
Water Beads + 100 plastic test-tubes & spare fishing line: $24.00
Yup. You read that right. Check out how it's done below: