Unfortunately that is very typical of Asian factories. You are at the mercy of their knowledge and network. They will not say they don’t know but rather say it can’t be done. Anything can be done in Asia, your development partner just has to do the legwork and find the correct suppliers.
There are plenty of RP houses in Asia to choose from like Star Rapid - Low-Volume Manufacturing & Prototyping http://www.rpprototype.com/ to name a couple but it is up to your partner to convince and educate your supplier. Browse their websites and you can see the list of materials they can RP or machine.
Like iab said, prototype them in NA, work out all the bugs and then send it back to Asia. It will be more expensive but the alternative is to convince your supplier to try something new to them…even if it’s a simple as machining raw material. We just had 2 pieces that are like 16"x 22" out of plastic in Asia. It was way cheaper than RPing them in the US.
Accura Materials or Polyjet materials will do the job. Just don’t expect them to behave exactly like molded parts. After all they are created using an additive process so they will always be more fragile. Talk to the RP houses and see what materials they will recommend.