If there are several parts in one product, the structural engineer may not find all interferences among the parts by checking in 3D files. At this point, a prototype is needed to verify the internal structure design. the prototype must be made accurately in dimension. The prototype is mainly used to verify whether there is any interference between parts or some of the product functionality cannot be met due to the wrong material selection.
So you should clarify this purpose when you ask for quote, it can help us to choose the best solution for you to save lot of manufacturing time and cost.
If you need to verify the part assembly, we recommend using SLA for processing, which can save you a lot of money. If you want to confirm the assembly result and surface treatment effect at the same time, then CNC machining is the better solution to make the prototype.
Let us know what the purpose of your prototype is when you ask for quote. it is very important to help you saving cost. Sometimes even 50% of the manufacturing cost can be saved, depending on the different types of surface treatments.