First: Sorry it's my first post. Now that that's out of the way I also want to say I didn't read all of the suggestions: I browsed through the first 8 pages and the compendium and didn't see this idea, though there is a thread on the [now] 3rd page with a similar title. I also didn't notice this on the list of already denied ideas, unless it falls under "new crafting table" which is a bit of a simplification.
Replicator: unlike the other thread I'm thinking very much like Star Trek, just not quite so egregious. I'm suggesting a top tier machine that could possibly replace current UU matter crafting, or at least supplement it greatly. The Replicator could accept UUM as a type of fuel and manufacture completed machines within a short duration. The machine would of course have to be powered and have a sufficient supply of UUM, and with 1 iron ore being 2.5m EU, advanced machine replication would require a dizzying supply of it. The true pinnacle of Industrial Technology. It could/would/should even be more expensive than taking the UUM, making the base materials, and crafting the machine by hand.
Let's take a generator: Machine block (10 UUM for the 4 ore required), Furnace (Cobble can't be made with UUM so let's just say 1; it's certainly not more expensive or rare than sandstone), Battery (I'm going to break it down into fractions of current crafting and then sum at the end [1.2m for tin, 1/3m for redstone, .1m for copper and 65k for rubber = ~1.7m EU =~1.7 UUM]) total value of, let's say, 13 UUM to make a simple generator from scratch with nothing but UUM in the Replicator. That's for a basic, coal burning, gets cannibalized to build something better in day 2 generator.
Using the established numbers, making a mass fabricator with this would be 82.768 UUM. Round to say 85-87 to add in the extra effort and EU spent processing some of the materials.
After you've set up a multi fabricator factory being fed by a recycler room being fed om turn by a cobble generator, don't you deserve to make more whatever-you-wants with the push of a button instead of all the tedious clicking and moving it takes to make the higher machines?