Coverdinbriefs, the slime is made by sprinkling moisture retaining cyrstals into the pool with warm water, then adding a little water based lubricant. The slime can be made as thick or as runny as you want it.
Inspired I gave it a go. I got some "water absorbing crystals" used to water hanging baskets, and mixed with j-lube and black poster paint! Made a little bucket of nice sticky slime.