[Chris Nafis] crunched the numbers and found out he could get filament for his 3D printer in bulk for about one-fifth the cost of the cartridges the company sells. This led him to print a feeder ...

3DSystems' cubify.com also offers a myriad of designs, but many of these are not free. You can browse both sites to get an idea of what's possible with 3D printers. Once you have a design you're ...