Here is certainly a practical and cost saving application of 3D printing. A German man named Marek Senicky, who also happens to be the creator of the Filamaker, has 3D printed a 33 piece compost grinder for his kitchen. The grinder can withstand up to 70 newton meters of torque and will cost a total of $60 to construct. Senickey plans to continue to improve upon his creation, and has posted it on Thingiverse for anyone to download and print out themselves. More information on this awesome 3D print can be found here:
http://3dprint.com/5563/3d-print-compost-grinder/

Here is a picture of his compost grinder: