All the customers have this confusion. Let me introduce this process below.
1.According to your drawing and requirements for the materials. Our main products is un-finished casting products. So, usually the buyer/customers know this specification very well.
We produce the sample and send it to customers for your test. We arrange the final production if our samples can be accepted.
2.According to your samples. We can make the 3D drawing and analysis the content of materials in our lab. You will confirm this 3D drawing and relative analysis. We offer the price and arrange the production.
Of cause, I just simply introduce this process. We must have many details which needed to be confirmed when we really begin to cooperation.