Dig a hole that goes down two blocks in the star formation you see above.
Place one sticky piston and surround it with four redstone.
Place any sort of block on top of each redstone.
Place your one slime block above the piston.
Finish it off with four pressure plates surrounding the slime block. Sprint diagonally and once you touch the pressure plates you will be launched into the air. I hope this is useful! :) Enjoy