A 3-D printer. It would basically be a replicator from Star Trek or other Sci-Fi. Essentially takes 3-D ink (pixels?) and converts it into the structure of complete molecules in the shape of the desired object. The requirements would be the blueprints or design for the item you wish to craft, plus either raw materials or pixels. Raw materials would be less expensive, but pixels would be more convenient. This may or may not be available early on. Tiy already talked about 3-D printers and using the ink as currency in the Live Chat.
I think it would be cool to have a multi-mode holo crafting table where you could make things like weapons to armor and all kinds of things. and you could switch the mode of it like its on tools you can set it to weapons or blocks. and when you use it a hologram of a crafting interface would show and you put your items in there and then i rattles and shakes as it makes the object then spits out the object of a vent of some sort which could be hooked up to a pipe and sent to a chest for say mech parts. Jolly good show chap!
There may be a system that let's you craft with items that got prefix buffs like weapons have in Terraria. Imagine combining your <Heavenly Powerdrill> with some <Mighty Adamantium> and you would get a <Godlike Powerdrill of Doom>, whereas you would only get a <Godlike Powerdrill> (without doom) if you where to use a normal powerdrill. That way you can hunt for the items with the rarest prefixes, combine them and create a super expensive ultimate item. That's a would be great, right?