Rubber farming!

Guess what? THE RUBBER TREE SAPLING FINALLY GREW!!

 Now I can finally tell you how to get rubber from these. You hit the yellow spots(right-click) with the treetap, which makes them drop

You then cook it in the furnace to get rubber.

It's that simple. And there are also machines you can make(in the Technic Mod pack) that let you get more rubber from the Sticky Resin and rubber from the wood of the tree and those huge trees we saw before. 

But we'll get there when we get there.