First of all, for those who don't know gak; gak is basically a cross between Silly Puddy and the Slime you used to play with as a kid. It is slimy, stretchy, pliable, as my sons says "melty", it's wet but dry at the same time. I can be less messy then play dough (as long as you don't just let it sit on fabric or on a surface for too long, because it will "melt" onto the surface.)
2 - 4 oz. bottles of Elmers Glue (you can use the clear or classic, I used the classic)
1 tsp Borax
Pour the glue into a large bowl, fill the empty bottles with warm water, shake and pour into the bowl. Add food coloring (more that you think, I thought I used a lot but as you can see it isn't very vibrant.) Add an additional 1/2 cup of warm water, and the borax. Stir into the glue mix, stir for a bit then get our hands in it. Knead/blend until you can form a ball. There will be a lot of liquid left in the bowl, that is normal. Remove the
glob ball, when it is not being played with store in a zip top bag or plastic container with a tight lid.