Pictured is a cool spray humidifier. This type of humiditier has been all but ignored on the web. This is kind of odd, because this type of device has many advantages over ultra sonic humidifiers that are fairly popular.
Also pictured is a 12 event digital appliance timer available at large hardware stores and other stores such as Walmart and K-mart. This one is the "Intermatic" model DT7. It costs somewhere around $20. It allows for 6 ons and 6 offs during a 24 hour cycle so you can turn on the humidifier for one minute (minimum time on) or more and then off for 3 1/2 hours, and then on for a minute and off for 3 1/2 hours ect - during a one day period which will repeat indefinitely.
This humidifier must be used very sparingly. In humidity charging a large chamber the size of a bath tub, a one minute on time can bring the humidity up to max within the minute. The important thing to remember, is that these humidifiers will super humidify a small chamber in less than a minute. When you first rig the chamber up with the humidifier, check the humidity and control it. Check the cakes closely and if you see any water droplets building up on the cakes, the humidifier must be cut back. You can always make the opening of the outlet tube smaller by covering it with a tubing end cap (plumbing dept.) and drilling small holes in it to diminish the humidity output.
When you use the humidifier, put just about an inch of water in it (ignore the instructions which says to fill it - a gallon or more). This keeps it cleaner and gives more room in the misting chamber (inside the unit where the siphon tube and misting assembly is). Since the unit will be used sparingly, a small amount of water will suffice. And with a lower water level, the tubing connection hole can be drilled into the side of the unit with room to spare.
The unit pictured, had a slit opening on the top for the mist to come out of. I glued a white piece of plastic over it and drilled a one inch wide hole next to it for the plumbing screw connector.
This is a mystery. The hole drilled in the unit measures one inch across (one inch hole saw - attaches to an electric drill). But the plumbing stuff says 3/4" inch!?????? Measuring the outer diameter of the "3/4" inch tubing reads one inch. I guess it is that plumbing jargon that keeps the rest of us in slaved to the plumbers. Take a ruler with you when you get your supplies and measure for one inch circle diameters of all the tubes and hole saw.
Use "3/4 inch" (that is what it says on the tube!!!!) thin wall plumbing tubing. Get the thinest type. This is used for such things as sprinkler systems ect. It is very easy to cut and rig up. But know that it measures one inch in diameter with a ruler! Go figure?
To rig it up into a chamber takes just a simple one inch hole for the outlet tube. You can tilt the tube so that it either points in an upward direction (prevents tube dripping free water on the cakes) or downwards (dripping out).
The lid affair to the chamber can be a little "leaky" for air. Just prevent it from allowing drafts of dry air in. Air tight is not needed, just tight. This way, the air coming from the outlet tube from the humidifier can rush in unimpeded by any positive air pressure from an air tight chamber. But make the lid so that it will hold humidity.