Add borax powder to 1 cup of water and stir to dissolve. Set aside. Pour glue into a medium mixing bowl and add 1/2 C water. Add a few drops of food coloring until desired color is reached and then stir to mix glue solution until smooth.
Pour the borax mixture into the glue mixture and watch the solids start to form. Stir for a few moments and then use your hands to gather the mass.
The mixture will be very soft and wet. Keep kneading until it firms up and feels dry. Discard excess liquid in bowl.
The more you knead and play with the slime the firmer it will become. Store in a Ziploc bag or air tight container and the slime will keep indefinitely.