Well, the effects of (and conditions which are treatable by) vaporizing are very different than those of juicing the fresh leaves of a plant with a different chemical makeup than the one you would vape. The reason for using one are to activate the psychoactive elements in the plant which must be heated. The juicing is done raw so there are no psychoactive effects.
The leaves of cannabis should provide as much juice as most any juicing leaves, but I've never done it. The requirements are far too difficult for me to meet.
I did a cursory search and found this on YouTube https://www.youtube.com/watch?v=7xPmR8j4plw
I think this is the same video I saw a few years ago that had some helpful info in it, but I can't watch it right now to be sure.
There are some further links in the comments section as well. I have heard a lot of good is coming for those who can manage to do it.