The cost of rapid prototyping has been plummeting lately with open source products like the RepRap and MakerBot, but now it’s hitting a new low…$500 for an extrusion style rapid prototyping machine from Solidoodle.  What you save in money, you sacrifice in layer resolution…this Solidoodle, for example, uses 1.75mm extruded material so the parts have a definite stairstep look to them.  Still, it’s awfully impressive and even that limitation can be acceptable for a lot of uses (especially if you sand or fill the parts to smooth out the layers after building).  While material selection and build resolution are nowhere near as good as more expensive processes like SLS and SLA, this is a market that just didn’t exist a few years ago, and is quickly growing.  For those who don’t want to learn how to make their own 3D files, there are even websites like Thingverse where people can download files ready to print.