The word prototype covers everything from a printed shape you hold for ten seconds to a fully functional unit that goes on test for six months, and suppliers who serve those two ends of the range are different businesses. Working out which one you are buying from is the single decision that decides whether the quote you receive is competitive or irrelevant.
Three kinds of supplier, three kinds of quote
A print bureau sells machine time and finishing and quotes from a file in minutes. A machine shop sells setups and cycle time and quotes from a drawing in a day or two. A product development house sells engineering hours and will quote a project rather than a part. All three call themselves prototyping suppliers, and only one of them is the right answer for any given request.
What to send so the quote comes back usable
A solid model in a neutral format, a dimensioned drawing where tolerances matter, the quantity, the material or a functional description of what the material has to survive, and the date the part is needed. Quantity and date change the price more than most buyers expect, and leaving them out invites a supplier to guess conservatively.
Reading a prototype quote
Look for the split between setup and unit price, because that tells you what a second batch will cost. Look for what finishing is included and what is extra. Look for whether inspection is included and to what standard. And look at the lead time clock: many quotes start counting from receipt of an approved order and a clean file, not from the day you asked.
Signs of a supplier worth keeping
They come back with questions about function rather than only a number. They tell you when a cheaper process would answer the same question. They flag a feature that will be a problem in production even though you only asked about a prototype. That last one is worth more than a discount, because it moves the cost out of a tool you have not cut yet.
Questions people ask about prototyping services
What is the difference between a prototype and a pre production part?
A prototype answers a question. A pre production part proves the process that will make the production ones. They can look identical and are bought for opposite reasons.
Do I need a drawing, or is a model enough?
A model is enough for a shape check. As soon as a dimension has to be right, a drawing with tolerances and datums is what makes the supplier accountable for it.
How much should a prototype cost?
There is no useful benchmark, because the same geometry can be printed for a few dollars or machined from a certified alloy with inspection for several hundred. Decide what the part has to prove first, then the price range follows.
Can one supplier take me from prototype to production?
Some can, and it removes a handover. Check that they are genuinely set up for the production process, because a shop that prototypes beautifully may subcontract the tooling and lose the thread.