I don't know about RepRap, but one of the few that can mill and print that I have seen is the Sumpod - though I'm not sure what it can mill as I think the drive system has to set up differently on milling machines.
I'm currently debating whether to buy a SumPod or an Ulitmaker, the ultimaker can't mill but does amazing prints at high speed. I do want a machine capable of milling but I'd want it to do mostly metal stuff which I think is beyond the capabilities of the SumPod. Though at £250 for the mdf it seems one hell of a machine!
That's what I thought, I was surprised that it would even mill MDF.I would not even bother thinking of milling metals on it. It needs a LOT more grunt and stability than what even most low cost machines can supply.
Can you print a engine, small parts?
Can you print a handgun?
What cant you print?
can someone who hasnt used anything like this before grasp this without needing to learn for months on end?
Seriously tempted
That wrench video is one of the coolest things i seen
Can a 3D printer draw a 3D printer. if so how much would it cost to make I wonder and could I then return the original
Depends. You can get loads of plans on Thingiverse, but ideally you need to be able to model in 3D. I can 2D and 3D draught and use solidworks etc, but Google does have a nifty program called inkscape. (IIRC)
You need to be able to model what you require, and then run it through a program called replicatorG (at least for the makerbots and mendels etc) which tells the machine what to do. They are certainly not plug and play, but they are pretty close!
It is a potential issue in the USA though, due to local laws. It's possible in the USA to buy the unprintable parts of a gun without a licence. It is therefore possible to print the part of a gun that requires a license, buy the unprintable parts without a license and assemble them to make a working gun without having a licence.
You might be able to print some other form of gun that involves lower forces.