I've cut plastics on my CNC machine that has a palm router as the spindle. Just get a bit/endmill made for plastics and it will work well. If it's not an appropriate bit you'll just end up melting the plastic and essentially melting instead of cutting along the edge.

If you're on a budget, go for the cheap sets of 10 endmills available on Amazon. You get 10 endmills for way less than the price of one good quality one and they're "good enough", and certainly a good starting point for learning and making mistakes. Nothing's more disheartening than breaking brand new $30-$50+ endmills on your first test run...