Gels for DNA electrophoresis are made using agar, a powder made from various kinds of seaweed that can be used to thicken foods, create gels or make growing media for microorganisms.
Agar agar (as opposed to nutrient agar) is used when making gels for DNA Electrophoresis. Weigh out your agar. Add it to a flask. Put in the correct amount of distilled water and cover the flask. Heat in microwave until clear (about one minute) and then let cool until comfortable to hold. Pour into tray.