Originally Posted by
RossMosh
Without knowing the size or use it's hard to help but my gut says you should be cutting a master and having it molded and mass produced. There are a bunch of different types of waxes that machine really well and fast and might be ideal if that's an option.
If that's not an option, I'd be thinking hard plastic like Delrin. This is not my field of expertise so I'd call around and try to find someone that's a plastics expert or simply talk it over with your client. They should know something. I will say expanded PVC would be close to the bottom of my list. If MDF is breaking, I wouldn't go with HDU either.