How to Create
The Flowing Slime Material can be collected from Re-animation Station. The stretchy behavior can be done with the dephysicalize tool.
Run Sackboy, Run!
The material makes an appearence in Run Sackboy, Run! Unlike LittleBigPlanet PSVita, Sackboy slows down once he steps on it, which causes the Negativitron to have a chance to destroy him.