Big machine.
You fill the feeder bin with all your Legos. It automatically sorts them by color and shape into its internal bins.
USB connection to your PC on which runs the software. You download the structure you want from the web site. It builds it for you. If it encounters any problems ("need more blue half-tall 2x3") it reports on screen.
Or, you may build something cool yourself and the device will reverse engineer it into an uploadable program you can share on the site.
NOTE: I know that this device is needed in order to bake "Kong for a day", but it ocurred to me that it was a half-baked thing in itself, so here it is.-- globaltourniquet, Aug 22 2007 Lego Production Line Built of Legos http://jalopnik.com...ego-cars-291396.php [Laimak, Aug 22 2007] At first this seemed magic, but it could be done. If the blocks were right side up and ready for grabbing it would be easier. The robot arm would track over a square like one of those grabber claw carnival games. It would descend with the appropriate block into the appropriate grid, and track was was there virtually, as a sort of tetris.-- bungston, Aug 22 2007 That would make such a great practice project for budding roboticists, I'm surprised it hasn't been done yet.
Easy: Finding and sorting pieces. Hard: Taking models apart and putting them together - you have to grip and push and pull things just so.
[Re: link: wow!]-- jutta, Aug 22 2007 That link is impressive. I'm not usually one to argue a "baked" but I would call that system "a start". It doesn't sort them, and I'm sure the item built is hard coded. Plus, my system doesn't need to be made out of Lego, but the fact that that machine is is quite amazing.
But it proves it isn't magic, yes?-- globaltourniquet, Aug 22 2007 Yup. I didn't mean to imply that it was baked.-- Laimak, Aug 22 2007 If you've ever watched a robotic assembly line construct a circuit board (or a car) you'll know that this is very possible to do.-- marklar, Aug 23 2007 One day I would like to try and implement this in Lego - a form of von Neumann machine. [+]-- Srimech, Aug 24 2007 random, halfbakery