Going too slow is often worse than too fast in plastics. I'd treat it like a piece of pine with some "moderate" aggressiveness. I'd also set up a compressed air flow to clear the swarf and keep everything cool. Once you're about an inch into the material you may want to insert some wedges in the cut behind the blade to keep the cut open. Tapered wooden shims would probably be ideal.
When you go to mill it pay attention to how hot it gets, otherwise it will warp. Use fairly shallow cuts, High RPM, heavy feed and a mist coolant. Also flip the part frequently.
When you go to mill it pay attention to how hot it gets, otherwise it will warp. Use fairly shallow cuts, High RPM, heavy feed and a mist coolant. Also flip the part frequently.