Say I have a bucket full of lava, the lava I'd want to use and the bucket I'd like to keep. From what I remember vaguely, you could call a transform on CraftTweaker to simply change it to the normal bucket or something, in effect, 'using' the lava bucket and keeping an empty one.

Is there a function(or whatever those are actually called) for not consuming an item used in a recipe?

Duplicate of #55

For reference, this is being worked on, but only sporadically unfortunately as neither of us have the time currently ^^