If you store your toolbox in a non-climate-controlled garage or shed or in the bed of your truck, rust prevention is very important. You could collect a few of those tiny silica packets that come with a new pair of shoes, but it could take months (or years!) to have enough to protect your tools from excess moisture.
Instead, make your own rust-preventing pouch using a generous scoop of silica crystal kitty litter, a piece of breathable fabric (we cut off a piece of an old t-shirt) and a zip tie.
Toss the pouch inside your toolbox to keep your tools rust-free. You can make several pouches with one bag of kitty litter. Heck, make some extra pouches and gift them to your friends for the holidays!