Growing mushrooms is a rewarding task, whether you're a gourmet growing for the kitchen or just a hobbyist growing for fun. Mushrooms are, though, very finicky fungi. Without the proper environment and care, they won't grow at all. Luckily, building a mushroom incubator, which will regulate your mushrooms' temperature and keep it perfect for growing, is simple and relatively inexpensive to make.
Place the water heater in the middle of the slightly larger container. For safety reasons, you may want to place a piece of tin foil or other substance under the lamp to keep it from touching the plastic directly. This is not strictly necessary, however.
Fill the container with enough warm water to totally cover the heater. The water should be around 80 degrees. Set the heat controls on the water heater to this temperature (80 degrees). You may want to wait an hour or two for the next step, so that the heater can begin regulating the water temperature.
Place one support near each corner of the container. The second container will rest on these. Make sure the supports are higher than the lamp.
Place the smaller container inside the first, resting on the supports. Make sure the first (bottom) container is about half full of water. If necessary, add more.