1) You can make a dog bowl from any container that can hold water. As long as it doesn't leak, it will work as a bowl.
2) To keep water from getting cold or freezing, it must have some sort of heating element. You can buy a bowl that gets plugged in at a farm supply store for probably less than buying the unit separately and attempting to make it yourself. It doesn't heat the water, just keeps it from getting too cold. If you want to, you can attempt to use some sort of solar element that will keep the water from freezing.
3) You cannot stop evaporation from happening--it scientifically will happen unless the bowl is fully enclosed. If fully enclosed, you will not have access to the water. In order to be able to access the contents, some evaporation will happen. Period.
4) Insulating a bowl won't stop the contents from getting cold and won't stop evaporation.
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