When a CAD file lands in our inbox with no context, the quote takes a week longer than it should — not because we’re slow, but because we have to email the engineer back with eight follow-up questions before anyone can actually price the job. Most of those questions could have been answered in two paragraphs sent alongside the file.
Designing for additive (DFAM) isn’t just about geometry — chamfers, draft angles, minimum wall thickness. It’s also about giving the supplier enough context to recommend the right material, the right build orientation, and the right post-process path. Here are the five things to send us before you send the CAD, in rough order of how much they speed up the conversation.
1. What the part actually does
Geometry alone doesn’t tell us function. A part can look like a bracket and actually be a fixture, a shroud, a strain-relief, or a housing — and the right material, build orientation, and tolerance budget changes for each.
The two sentences that unlock the most useful supplier recommendation: “This part does X under Y conditions. The failure mode I’m worried about is Z.” That’s it. Once we know what the part has to survive, we can match it to a material profile that survives it.
When function isn’t stated, suppliers default to the most conservative material and the most expensive build orientation — which usually means you’re paying for performance you don’t need. State the function and we can do better.
2. The environmental envelope
Material selection for additive lives or dies on environmental conditions, and “indoor use at room temperature” is a real spec that narrows the field by 60%. If the part sees any of the following, tell us upfront:
- Temperature range — operating and maximum. A part that lives at 80°C ambient with 110°C spikes is a different material conversation than a part that sees a steady 25°C.
- Chemical exposure — solvents, fuels, oils, cleaning agents. Some additive resins survive isopropyl alcohol fine and dissolve in acetone. The chemistry compatibility chart matters.
- UV exposure — outdoor use, sunlit interior, none. UV degradation is real for many photopolymers.
- Mechanical loading — static, cyclic, impact. Tensile strength is one number; fatigue performance is a completely different number.
- Humidity / water contact — nylons absorb moisture and change dimension; some resins do too. Worth knowing.
You don’t need to be exhaustive. A single line — “lives inside a sealed enclosure at 60°C ambient, no chemical exposure” — closes off three quarters of the material decision tree.
3. Which dimensions actually need to be tight (and which don’t)
The single most common DFAM mistake is over-toleranced drawings. An engineer ballparks all dimensions to ±0.001″ because that’s what their CAD template defaults to, and the supplier has to either price every feature to that tolerance or send the drawing back with questions.
The fix is a hierarchy. Mark the dimensions that have to be tight — the ones that mate, that seal, that bear a load — with the actual tolerance they need. Leave the rest at a reasonable default for the process (typically ±0.005″ to ±0.010″ for industrial SLA and SLS).
This isn’t a corner-cutting move. It’s giving the supplier permission to use the process’s natural capability instead of fighting it. Build orientation, post-process choices, and inspection sampling can all be optimized when the supplier knows where to spend the precision budget.
4. Surface finish and cosmetic requirements
“Surface finish” is two different conversations for additive — and they have very different cost implications.
The first is functional surface roughness: does the part need to seal against an O-ring, slide against a mating part, hold an adhesive, accept a fastener thread? Those needs are objective and quantifiable, and they drive post-process choices like vapor smoothing, bead blasting, or secondary machining.
The second is cosmetic appearance: will this part be seen by an end user, or does it live inside a sealed enclosure? Layer lines, build-plate artifacts, and color uniformity all cost real money to eliminate. If the part is invisible in the final assembly, say so — and we’ll skip the cosmetic post-process steps that don’t change function.
Tell us which surfaces are critical, which are functional, and which are invisible. The quote will reflect the work that actually has to be done.
5. Production context: volume, cadence, and timing
A 50-piece prototype run and a 5,000-piece production order are two different jobs with two different optimization strategies, even if the part geometry is identical. Knowing the production context upfront lets us nest the build plate, plan post-process batching, and quote a realistic delivery cadence.
What helps:
- Estimated annual volume (a range is fine — “5,000 to 10,000 per year”)
- Order cadence (one big run, monthly, on-demand?)
- Required lead time for the first delivery and for refills
- Whether this is a one-time job or an ongoing program
The “one-time prototype” path and the “annual program at volume” path use the same printers but very different production planning. The right path quoted from the start saves a re-quote later.
The one-page brief that saves a week
None of this is a long document. The supplier-friendly version is a one-page brief that includes: what the part does, where it lives, which dimensions matter (with tolerances), what the surface needs to do, and how many you need per year. Send that with the CAD and you’ll typically get a quote in hours instead of days, and the quote will be priced against the actual job — not against the conservative defaults a supplier has to assume when context is missing.
The fastest way to get a good additive part isn’t to send the CAD sooner. It’s to send the CAD with two paragraphs of context. The DFAM conversation that follows is shorter, cheaper, and lands at a better part.
Ready to see what your part would cost? Upload a CAD file for an instant estimate, see what we run on our capabilities and materials pages, or talk to a real person about your project.