Revert something you crafted to its raw ingredients?

Is it possible to break an item down to its raw ingredients? Such as breaking an Iron Bar into 3 Iron Ore?

On a similar note, is it possible to undo something you've built right after building it (before using it or placing it in your inventory)?

Since it's only one button click to make something, I've made something by accident on more then one occasion, which is fairly annoying. So it would be nice if there was a way to undo this.

There is currently no way to reclaim things in this manner with very few exceptions (like arrows).

I think it would be a good suggestion (at the terrariaonline forums) however as after the third time the eater of worlds dropped the greaves it would be nice to salvage it and make a helmet instead! :)