Needed a reliable supply of slime balls for future projects, then decided to go all out on the project, first I cleared out a pair of 24x24 rooms from level 40 to bedrock, making very sure to centre them over chunks that are capable of spawning slimes (I used this utility to find the slime chunks), then I inserted a collection canal system and 4 fall breakers into each of the towers. After that I built reducers, hooked them up to a 'storage tank' using pistons and put in wiring to either vaporise the slimes or allow them to flow through, after all that I built the floors, six of them per tower.

I certainly have plenty of slime balls now :)

The rooms were cleared mostly using tnt (24x24 is convenient as it is divisible by the blast diameter of TNT in stone ;) The gunpowder required for this amount of TNT was acquired through use of another project that I completed a couple weeks back :)

texture pack is misas Hdpack.