Interesting fact.
Aside from the really broken part, the part that would corrupt your world, there was a dupe glitch with it.
The blueprints would copy the meta data of the blocks, but the builder would only require the regular block to build it.
So you could fill an iron chest with diamonds, make a blueprint of it, then use the builder with an empty iron chest. You would dupe all the diamonds.
There was a vid of someone using that to dupe redmatter back on 1.2.5. They made it into an automatic EMC generator that made an alchemical chest worth of redmatter every second.