How do I get slime? Or is it not implemented yet?

I don't think it is implemented.

Ah thanks, I've managed to add it using witchwater and a leaf block in a stone barrel. For what I need this works fine.

I am working on a method of obtaining slime. Glad that you have something that works in the meantime.

I have added a branch where milk+mushrooms makes a slime block while spawning up to 4 small slimes nearby.

That sounds like an interesting way of doing things.

Added with 598525e