This is a salt dehumidifier for storage boxes.

Normally when I put things away for storage in the garage or in the attic, I put my stuff in a plastic box with lid and then I put in a small can with some calcium-chloride salt. This is great at keeping the air inside the box at a low humidity and the stuff in the box free of mold.

However metal cans and salt is not great together so I made this plastic salt container. It has a top and a bottom. The top contains the salt that absorbs the humidity in the air. It has a small hole in the bottom so water can drip down in the bottom part. The two parts are sealed with a O-ring and held together with three bolt and can be separated so you can empty out the water when it is full.

Note. The size of the holes are made for a brass insert. I will publish a version with smaller holes shortly.

You can read more about it here http://metal4plastic.com/blogs/insert-blog