Slimestone

Slimestone is an uncommon stone type that only spawns in slime chunks. Slimestone slows you down slightly when you walk on it, and it drips slime. Place a cauldron below it to slowly collect slime, and right click the slime cauldron (with anything) to obtain slimeballs. You can also craft 4 copper and 1 slimestone together (in a clock/compass formation) to get a slime sensor. Whenever you're in a place where slimes can spawn, any slime sensors in your inventory will "glow", which can be useful for finding slime chunks.

This would make slime much easier and more intuitive to obtain.