First you had to open up a high-lighter pen and run cold water on it catching the liquid in a cup.
Then mix the liquid with the glue and borax and give it a good stir.
We used white glue here because I'm a cheap skate and wouldn't use any new clear glue until we'd used up the old stuff :o)
The white PVA glue didn't work very well,(sort of ended up with a bouncy ball) so we did another batch and used the clear glue which worked really well and we ended up with flourescent slime.
This is it under the black light, quite impressive.Below are pics of cornstarch and water mixed together to show how polymers act (as a solid when pushed together and as a liquid when left to run down your hand).
This had my son engrossed for quite a while.