I'm in the process of making sets of drawers to house my tools (magnets on the wall are REALLY good but too much dust). I have three questions about using silica gel sachets

1. The most important question is if I put SG in with rasps and files that have hardwood handles is there any danger of the local atmosphere getting too dry for the timber and leading to cracking?

2. In a drill tray 600x500mm, would I be better off putting say 4x 25 gram sachets or a multitude of 1 gram sachets (say one under every second drill or similar)?

3. Does anyone know of a better product or cheaper and as good as the one in the link above? I like the idea of an indicator to show when the gel is "full".

Thanks, Brett