Back in 2019, I told my production manager that 3D printing would never leave the prototype bench. Then a customer asked for a surgical guide with internal cooling channels—geometry no solid carbide HRC58 end mill could touch. We ordered a Formlabs part, and it worked. But it worked because I stopped guessing and started inspecting. Since then, Formlabs has grown from a crowdfunded SLA printer into a full additive manufacturing company: desktop and industrial systems, a broad engineering resin portfolio, software, and their own print service. That breadth is useful, but it doesn't replace validation. I'm the quality inspector who reviews roughly 2,000 parts a year before they ship. In 2025, I've already rejected 11% of first deliveries for tolerance or finish issues. If you're proposing a Formlabs additive manufacturing company part for production, this is the checklist I use. It isn't glamorous. It works.

Before You Start: Does This Apply to You?

This checklist is for anyone who wants to use Formlabs SLA or SLS parts as end-use components, not just visual prototypes. It applies whether you're printing in-house on a Form 4 or ordering through the Formlabs website's print service. If your part will face mechanical load, temperature, or regulatory review, work through the steps in order.

Step 1: Pull the Real Material Data

Go to the Formlabs website and find the technical datasheet for the exact material you're considering. Not just 'the clear resin'—the exact product SKU. Check tensile modulus, flexural modulus, HDT at 0.45 MPa, elongation at break, and water absorption. Compare every value against your design requirements. Per FTC guidelines (ftc.gov), advertising claims have to be substantiated, so the numbers usually come from real lab tests. But they're tested on standard coupons. Your part geometry may behave differently.

Checkpoint: if any datasheet value is below your design minimum, cross that material off now. Don't plan around it. (note to self: never assume post-curing fixes a resin that's below spec.)

Step 2: Build a Tolerance Study From Day One

Print at least five test artifacts with the same orientation, supports, and post-curing as your production part. Measure every critical dimension. Formlabs printers can be surprisingly good—z resolution goes down to 25 microns on some machines. But they are not CNC machining class. A CNC machining class part in my shop holds ±0.005 inch on steel. A printed part holds somewhere around ±0.1–0.2% of dimension. That's a different tolerance class.

I get why people assume a commercial printer is CNCs machining class because the marketing says 'industrial.' It's not. You can enhance printed parts to that level with post-CNC, but the base print isn't. In Q1 2024, we ran a validation batch of 30 printed housings. The XY axes were on target, but the Z axis shrank 0.4% versus the datasheet's 0.2%. We had to redesign a mating feature. If we'd skipped the tolerance study, the entire 500-unit order would have failed in the field. A tolerance study costs a day. A field failure can cost $22,000.

Step 3: Plan Post-Processing as If You're Machining

Once you hold a raw printed part, don't bolt it in as-is. Support nubs, layer lines, and residual uncured resin will sabotage the fit. If you're used to the finish from a solid carbide HRC58 end mill, an as-printed SLA surface looks rough. For functional parts, that might be fine—if you know where you can accept it.

Plan the post-processing before you print. Sanding? CNC machining critical faces? UV curing? Vapor smoothing? Each one adds lead time and cost. Post-processing is frequently unbudgeted. The last time I estimated it correctly, we spent about $18 extra per part on finishing. On a 2,000-part order, that's $36,000—not noise. (ugh, how many support-nobbed parts have landed on my bench over the years—don't be that person.)

Step 4: Specify Print Orientation on the Drawing

Orientation isn't just aesthetics. It determines which axis is weakest. SLA parts bond layer-to-layer slightly weaker than the bulk material. Printed flat, a tensile load spans multiple layers; printed upright, you're pulling the layers apart directly. When I compared identical tensile bars flat versus vertical side by side, I finally understood why the vertical one failed at 40% lower stress. It was one of those 'wait a minute' moments.

Write the orientation on the drawing. If you don't, the operator will pick whatever orientation fits the build plate best, and your mechanical properties become a lottery. The Formlabs website publishes orientation guidelines for each resin. Use them as a starting point.

Step 5: Qualify the Supplier (Yes, Even if It's Formlabs)

If you're ordering from Formlabs' print service or a third-party bureau, treat them like any sub-tier supplier. I've gone back and forth between a machine shop and a print bureau for a 200-unit run. The machine shop had tighter tolerances. The print bureau could produce an internal lattice we couldn't machine. I chose print, then spent a week wondering if it was the right call. The first batch passed. The second batch failed because the resin batch changed and the bureau didn't recalibrate. Now I always ask for:

  • Dimensional inspection report from the first article
  • Material certificate for the resin lot
  • Post-processing documentation
  • Evidence of calibration routine

If they can't provide any one of these, don't proceed. The same logic applies if you're bringing in a large-format printer for in-house production. Train the operators, maintain the machine, and run calibration prints on a schedule. I've seen more quality escapes from 'we just got this printer, let's go' than from any material spec.

Step 6: Don't Panic About '3D Printer Bans'—Do This Instead

Every engineering meeting now has someone asking 'are they banning 3d printers?' The short answer is no, not for professional additive manufacturing. Some jurisdictions restrict unlicensed manufacture of firearms or other regulated items, but that doesn't affect industrial SLA or SLS. Formlabs parts are used in medical, dental, aerospace, and automotive work every day.

What you should watch is regulatory approval for your specific application. Medical devices touching patients need FDA clearance. Flight hardware needs FAA conformity. Those pathways are still evolving, and the uncertainty can feel like a ban if your product is regulated. But it's not a ban; it's a workflow you need to budget for. To be fair, the ambiguity is real. Plan early, know your local laws, and check which Formlabs materials are biocompatible or regulated for your intended use.

Step 7: Budget for Total Cost, Not Just the Quote

This is where engineers get tripped up. The printed part's unit price is only the beginning. Include the tolerance study, post-processing consumables, calibration builds, inspection labor, scrap rate, and expedite fees if your deadline slips. Add those up before you compare with a CNC quote.

The value of a guaranteed lead time isn't speed—it's certainty. We once beat a quote from a cheaper bureau that offered 12-day delivery, then missed it by a week. We lost an $18,000 launch slot because the customer couldn't wait. The difference between 'estimated' and 'guaranteed' was $300. I've also paid a $400 rush fee on prototype resin and never regretted it. A part that arrives on time but out of tolerance is scrap, not a part. That certainty is why I'm willing to pay more for a reliable print bureau than for the cheapest job on the internet.

Three Mistakes That Still Show Up in My Inbox

Here are the ones that keep ending up in front of me:

  1. Treating printed plastic like machined aluminum. It's not the same strength, stiffness, or tolerance class.
  2. Not specifying orientation, layer height, and post-curing—then blaming the supplier for surprises.
  3. Choosing a vendor by the number on the quote instead of their delivery record. 'Probably on time' is the second most expensive phrase in manufacturing. 'Probably good enough' is the first.