Post-Processing 3D Prints for a Farm: Which Finishing Techniques Add Margin
Raw FDM output has visible layer lines, support marks, and a surface finish that ranges from acceptable to noticeably rough depending on layer height and material. For many functional applications, this is fine — the customer needs the part to work, not to look like an injection-molded product. For others, the finish matters significantly.
Post-processing — sanding, priming, painting, hardware insertion, assembly — is a natural service expansion for a print farm that already has the parts coming off the build plate. Done right, it increases the revenue per job without proportional increases in cost. Done wrong, it adds labor overhead that erodes margin faster than it adds revenue.
Here's which techniques are worth offering and how to structure them.
Support removal: the baseline
Support material removal is part of the base print service, not a post-processing upsell. Customers ordering parts with overhangs expect the supports to be gone when the part arrives. Factor support removal time into your base pricing for any job that requires it.
The techniques:
- Standard PLA/PETG support: snap and peel by hand, small pliers for tight geometry
- Soluble support (PVA, HIPS): dissolve in water or limonene respectively — requires dual-material printing capability
- Tree supports (Bambu Slicer default for many geometries): easier to remove than grid supports, less surface marking
Labor estimate for pricing: 5–15 minutes depending on geometry complexity. Factor this accurately — complex organic shapes can take 20+ minutes of support cleanup.
Sanding and surface smoothing
Sanding is the highest-demand finishing service and the most scalable. Customers who need smooth surfaces — display models, cosmetic parts, anything that will be painted — need sanding. The market for this is real.
The sanding workflow for PLA/PETG:
- Start at 120–180 grit to knock down layer lines
- Progress to 220, 320, 400 for smooth finish
- 800–1000 grit for near-polish finish before painting
- Optional: wet sanding at 1500+ grit for very smooth finish
Pricing sanding: charge by time, not part. A flat sanding fee of $15–30 for a standard part, more for complex geometry. Be explicit about the finish level — "sanded to 400 grit, ready for primer" vs. "sanded to 800 grit, near-smooth finish" sets clear expectations.
Where sanding doesn't make sense: functional parts where finish doesn't matter, high-volume production runs (sanding 200 brackets is not viable), and parts with internal geometry you can't reach.
Primer and painting
A primed and painted part is a different product from a raw print. For props, display models, cosplay pieces, and architectural models, painted output commands 2–4x the price of the raw print with material costs that are a fraction of the premium.
Primer: rattle-can spray primer after final sanding. Fills remaining micro-scratches, gives paint a surface to bond to, reveals any surface imperfections before color paint goes on. Gray or white primer depending on final color.
Painting: rattle-can spray paint for solid colors; brush work for detail, weathering, or multi-color applications. The complexity range is wide — a simple two-coat solid color is fast and low-margin; a complex prop with weathering, washes, and detail brushwork is high-skill, high-margin, and not a volume service.
Who to offer painting to: props customers, cosplay customers, theatrical clients, product mockup clients who need color-accurate representations. Not functional parts customers who just need the part to work.
Pricing painting: material cost (primer + paint) is low. Pricing is on labor. A basic single-color finish on a medium part runs 45–90 minutes including dry time; price at $35–60. Complex multi-color or weathered finishes are project-priced.
Hardware insertion and assembly
Many functional parts need threaded inserts, bearings, magnets, or other hardware. Installing hardware as part of the service saves the customer a step and creates a more complete product.
Heat-set threaded inserts: the most common. A soldering iron with an insert tip, thermal inserts, 2 minutes per insert location. This is a premium service that most customers either don't know they need until their prints strip out after a few screws, or that they want to outsource entirely. Charge $1–2 per insert for small hardware, more for larger or difficult geometry.
Magnet and bearing press-fits: parts designed with press-fit cavities for magnets or bearings just need someone to press the hardware in carefully. Low skill, low time, legitimate added value.
Light assembly: taking 3–5 component parts and assembling them before shipping. Saves the customer time; you're charging for your time. Price by actual labor at your standard rate.
Acetone vapor smoothing (ABS only)
Acetone vapor smoothing produces near-injection-molded surface finishes on ABS prints by briefly exposing the part to acetone vapor, which partially melts and smooths the surface. The output is genuinely impressive — layer lines almost entirely invisible, smooth to the touch.
The constraints: ABS only (PLA doesn't respond to acetone), requires proper ventilation and fire safety (acetone is flammable), and the technique takes practice to produce consistent results without over-smoothing or losing fine detail.
Worth offering if: you're already running ABS regularly for functional parts, your workspace has adequate ventilation, and you have customers for cosmetic ABS parts. Not worth setting up just for occasional requests.
What not to offer
Spray painting on high-volume runs: painting 100 units is not a print farm service, it's a finishing production line. The economics only work at scale with dedicated equipment.
Resin finishing: some operators offer SLA/MSLA resin printing for ultra-smooth output. This is a different machine type with different chemistry, cure requirements, and cleanup processes. Adding resin capability is a meaningful investment, not an add-on.
Complex custom paint work: unless you or your team have the skill and want to sell it as a specialty service, don't compete with dedicated prop and model painters. Refer that work to specialists.
Structuring post-processing in your service menu
The cleanest approach: a base print price, with post-processing as explicit add-ons:
- Support removal: included in base price
- Sanding to 220 grit: +$X
- Sanding to 400 grit: +$Y
- Primed: +$Z
- Single color painted: +$W
This makes pricing transparent, lets customers self-select the finish level they need, and gives you a clear scope for each job. Ambiguous "finishing included" promises lead to scope disputes.
Print Hive tracks labor time and job costs per order — so post-processing services are costed accurately rather than estimated into the base price. Start free →