14 November 2026
Drawing, sample, or requirement: what should you send a manufacturer?
You don't always have a fully dimensioned drawing. A practical guide to the three ways a custom manufacturing enquiry can start — and what each one needs to contain.
Most advice about custom manufacturing assumes you already have a complete, fully dimensioned engineering drawing. In practice, enquiries arrive in three very different shapes — and a good manufacturing partner can start from any of them.
Route 1: "I have a drawing"
The most direct route. The drawing — CAD model (STEP/IGES/DXF) or even a scanned sketch — tells the manufacturer what the part is, what it must measure, and what tolerances matter.
What helps most at this stage:
- Fully dimensioned views, or a CAD model with a dimensioned PDF
- Material and any required standard or certification
- Surface finish and heat treatment requirements
- Quantity and expected repeat rate
Any revision state is fine. Mark what is firm and what is still open.
Route 2: "I have a sample"
A physical sample answers questions a drawing never can: how the part actually fits, what wear looks like, what the real material behaves like. The manufacturer can reverse-engineer dimensions, identify material and propose equivalents.
What helps most:
- The sample itself, with any mating parts
- Context: where it failed, wore out, or underperformed
- Which dimensions are critical and which can flex
Route 3: "I have a requirement"
Sometimes all you have is a job description: "this shaft must carry this load at this speed in this environment." That is enough to start. An engineer can propose a design, and the enquiry becomes a design collaboration before it becomes a manufacturing job.
What helps most:
- What the component must do — load, speed, environment, life expectation
- Any constraints: space, weight, mating parts, standards
- Quantity and target timeline
What happens next — in every case
Regardless of the starting point, a serious review comes before any commitment. The manufacturer should come back with questions about manufacturability, material and process — and an honest statement of what can and cannot be made to the requirement. If a supplier promises everything immediately, that is the moment to ask harder questions.
The short version
| You have | Send it, plus |
|---|---|
| Drawing / CAD | Material, finish, quantity |
| Physical sample | Failure context, critical dimensions |
| A requirement | Load, speed, environment, constraints |
None of these is "better" — they are different starting points for the same engineering conversation.
Where to start
If you are weighing these three routes for a part you need made, the custom manufacturing page walks through what each starting point needs to contain — and the requirement form accepts any of them, at any level of detail.