Here is a new small 3d printer project that uses junk computer parts to create a low cost 3d printer. You will need three stepper motors from CD/DVD drives, one NEMA17 motor and some other parts. Entire setup will cost you under 100 US dollars.
Detailed build instructions and all the files can be found at:
Here is video of it in action and showing print results at the end:
On of the small weaknesses of this project is the need for separate lasercut wood or acrylic frame. It can be used without glue or screws.
For a earlier, more rough project with junk PC parts see: