Below are instructions on how to build a simple incubator.
Set up your aquarium/incubator in a area that does not get above 85 F. Place your bricks in the aquarium and fill the aquarium with water to just below the top of the bricks.. The submersible heater should be placed below the water line. Be careful not to let the water evaporate below heater! Next fill your plastic container with two inches of Vermiculite and water in a 2:1 (vermiculite:water) by volume. The vermiculite should be moist, but not watery.
You should set up your incubator a few days before your eggs are laid to make sure that you have temp set right. The temp should stay between 80 F to 85 F. When you remove the eggs from where they were laid, do not rotate them or turn them. Try to transfer them just as you found them. Dig a very small hole in the vermiculite to put each egg in, so that eggs-tops are just barely above the vermiculite (Figure 3). Do not move them after they have been placed in the incubator. Check vermiculite often (about every 3 days) to make sure it's not drying out. Use a small spray-bottle to spray AROUND the eggs, but not the eggs themselves. If the egg get, a shiny look to them, they are to wet. If the eggs start to collapse they may be to dry or they are not fertile. However if it is near the end of the incubation period, they will collapse right before they hatch.
There are two lids used in this incubator, one on the plastic container to keep the hatchling's safe from dropping into the water should they hatch in the middle of the night. The second on the top of the aquarium to keep the heat in (I used a board with holes in it for air circulation).
Figure 1
Figure 2
Figure 3 
For instructions on how to make a refridgerator size incubator, please go to the Karnivor web site at http://members.aol.com/KarnivorUtility/bator.html
