@TehEl1te yes i have seen a video of a guy build a new 3d printer and upgrades using a other 3d printer... and I was like WOW!!! a self replicate machine!
Regarding the DPI on 3d printers.
I have notice a video of someone making a human skull from a cat scan that was I would say at a guess 1/6 of scale (made from ABS), still looked good but still can see ridges...but when doing a 1:1 scale you chould see that there were a vast improvement regarding the smoothness and overrall looked way better.
IMO, I think that its the same issue that you have with current ink printers (you can only print so small before you start to lose detail). But I'm sure an higer DPI would help even if its small or large lol
But other things that I have come across is of course the material as some on the 3d printer suggest using thinner Filament to get a better finnish.
Of course this is one way of making a 3d object, and the reason that I have been looking ABS or PLA (I don't know what the differances at the moment) is that they seem to be the cheapest at the moment.
Also I did find this one
http://www.reprapcentral.com/vmchk/Mendel/...lypage.tpl.html
So far this is the largest one that I have seen, but I unable to find any reviews or any pictures of a end product from it. But even on the website its claims that its able to do a darth varder helemt in 1:1 scale has sparked my intrest lol, So I will be calling them up or email them to see if they can send a picture of it, as they don't have a picture on the website which is a shame.