I would just send the design out and ask for a quote for tooling with the material you want for the tool steel. You do not need to place an order, you are just asking to request a quote.
That quote should be valid for them to deliver on assuming the design does not change. If you have not sent it to any tooling vendors, then you may need tooling feedback to modify the design.
You should be able to request an NDA be signed by the tooling vendor before you send over information. With that said, China is China, and if your design is unique and easy enough to knock off or be copied then again keep that in mind. If you have any IP in place that would help.
I would not try and make a fake model just to get a quote, it will waste both your time and theirs which any business owner would not take kindly to.