Thinking to build a 3d printer... Ideas?

Well today i was in an IT class and we were learning about open source code and an open source 3d Printer was mentioned. I am thinking that it would be cheaper to build than it would be to buy one, any ideas on where to get instructions and parts? I'm sure someone here is into custom pc's and the like so i thought it wouldn't hurt to ask.

Thanks,
Jaxius

I think you can buy cheap kits online, still a few hundred $ worth but comparatively cheap. Accuracy of print is probably OK but if you're doing it for the exercise rather than having a high quality printer at the end, this is probably the best bet. A guy at my work has one at home that he spent a few hundred on and has since spent a lot more on modifying.

otherwise, you'll need stepper motors, toothed belts, equivalent drive shafts, toothed gears, a flat bed, more gears, probably a couple worm drives for the vertical motion, heating elements, tempered glass for the print bed, feeder nozzles, thermocouples, probably at least 3mm thick Al sheet with tools to cut precision holes to support all of the above in a high accuracy parallel plane.

My work has a Mankati printer that is fairly accurate with a heated print bed, but even then the printer is not reliable, we get about 1 in 3 successful prints, I would not buy this machine if you're worried about the amount of time you might need to spend babysitting it.