Effortless Cutting Blades?

knewter asks: "I've recently come across an application in a machine that my company is building in which we need to be able to cut a piece of hardened plastic without jolting the item from which we're cutting it. We've researched (mildly) some alternatives, and right now we're looking at ultrasonic knives. Unfortunately, these tend to be rather expensive, and as we're a robotics engineering firm, we'd like to keep the cost of the extraneous pieces of machinery negligible (this is a convenience feature). We've also looked at cutting it with a hot wire, but I personally am worried that this would taint the test results (it's in a sort of a plastic vial that is drained for testing purposes). Does anyone here have any ideas on what would be proper for this, or even some ideas on cheap nano-machinery (not in the sense of manipulating small particles, but in the sense that the blade has been refined to an extremely small point and will not require repeated sharpening)?" Of course, the obvious answer is a laser of some sort, but lasers aren't necessarily cost effective. How about high pressure water cutters?