Reptiles are fragile animals and a great amount of care must be taken by owners to emulate their natural habitats within their enclosures. Tropical animals, like Chinese water dragons or many chameleons, and amphibians like red-eyed tree frogs, require a great amount of humidity within their tank. Humidity can be increased by simply increasing the amount of moisture within the tank, which is often done by frequent misting of warm water. However, with a few tools and a trip to your local hardware store or pet shop, you can create a humidifier for your reptile enclosure that should help maintain adequate humidity.
Drill two holes, side by side, in the lid of the container. Make sure the holes are approximately 1/4 inch in diameter so that you can slide the plastic tubing into it, later.
Cut the plastic tubing in half using the utility knife, creating two tubes of equal size.
Place the lid onto the container.
Thread one of the plastic tubes, which will be the input tube, through one of the holes in the container's lid until its end reaches about an inch or so from the bottom of the container.
Thread the other tube, which is the output tube, through the other hole in the container's lid, but only by 1/8 inch.
Glue the tubes in place using the silicone sealant. Glue around the holes in the top of the container, securely sealing the tubes. Make sure that there is enough silicone so that there are no air gaps between the side of the tubing and the container's lid.
Allow the glue to dry for at least two hours.
Take the lid off of the container by turning the container itself. Do not turn the lid, as it may cause your tubing to get tangled.
Attach the air stone to the end of the input tube that has been threaded through the container's lid.
Attach the other end of the input tube to the output of the external air pump. The output is where air is expelled from the pump.
Place the humidifying sponge in the container and fill it about 2/3 of the way with warm water.
Place the lid back onto the container, once again making sure to turn the container and not the lid to screw it on securely.
Place the open end of your output tube into your reptile's enclosure. If it is a screen enclosure, you can probably just thread it through a gap in the screen.
Turn on the external air pump. The water in the container should begin bubbling and moisture should move up through the output tube and into your reptile's enclosure.