A 3D printing quote is calculated from far more than grams of plastic. Printers price the part’s volume and shell, infill density, support material, machine print time, post-processing labour and quantity. Weight is only one input, which is why instant quotes for the same file vary widely.
If you have ever uploaded one STL to three services and received three different numbers, you are not being overcharged at random. Each quoting engine weights these cost factors differently. This guide breaks down every variable, walks through two worked CAD examples, and explains why a heavier part can sometimes cost less than a lighter one.
Why isn’t a 3D print priced by weight alone?
Weight is a convenient proxy, but it hides three things a printer actually pays for: the time the machine is occupied, the support and waste material that never ends up in your part, and the human labour to remove supports and finish the surface. A tall, hollow, spindly model can weigh very little yet tie up a printer for 14 hours and need an hour of cleanup. A short, dense block can weigh more but print in three hours with zero supports.
Industry calculators confirm the real formula combines filament, machine time, electricity, labour and packaging rather than a single price-per-gram. Material weight itself is estimated roughly as volume × (shell + infill fraction) × material density, so even the “material” line already depends on your settings.
What are the seven factors in a 3D printing quote?
Here is how the cost of a typical decorative FDM print tends to break down. The exact split shifts with geometry, but the relative weighting is the useful part.
1. Volume and shell. Your model’s outer walls (the shell) are almost always printed solid, regardless of infill. Larger surface area and thicker walls mean more material and more time. This is the foundation of every quote.
2. Infill density. The internal lattice. A useful rule from FDM testing: going from 50% to 100% infill increases print time by roughly 40–60% but adds only 10–15% strength. For a display collectible, 10–20% infill is usually plenty, and it directly lowers your quote.
3. Supports. Overhangs need scaffolding that is printed, then thrown away. Supports, brims and rafts can add 15–30% to material use on complex geometry, and they are the single biggest reason orientation matters.
4. Print time (machine time). Estimated from volumetric flow rate (nozzle size × layer height × speed), not from weight. A finer 0.12 mm layer height looks gorgeous but can double the hours versus 0.24 mm. Machine time is often the largest single line on a quote.
5. Post-processing. Support removal, sanding, gluing multi-part models, painting. This is human labour and scales with model fussiness, not grams.
6. Quantity. Setup is a fixed cost spread across the batch, so per-unit price falls as quantity rises. This is why 10, 25 or 100 units unlock progressively better unit pricing.
7. Material choice. PLA, PETG, silk and specialty filaments carry different per-kilogram costs and different printability, which feeds back into both the material and the time lines.
Worked example: two parts, same weight, different price
Consider two models that each use about 45 g of PLA. The figures below are illustrative of how the factors stack, not a fixed price list.
| Cost factor | Model A — solid geometric vase | Model B — tall articulated dragon |
|---|---|---|
| Material used | ~45 g PLA | ~45 g PLA |
| Infill | 15% | 15% |
| Layer height | 0.24 mm (fast) | 0.12 mm (fine detail) |
| Supports needed | Minimal | Extensive (overhangs) |
| Print time | ~3.5 hours | ~11 hours |
| Post-processing | Light | ~45 min support cleanup |
| Relative quote | Lower | Up to ~2.5x higher |
Same plastic, very different invoices. Model B’s geometry forces fine layers, heavy supports and long machine time, none of which show up if you only weigh the finished object. This is exactly why a transparent quote itemises these lines instead of hiding them in a single per-gram figure.
Why do instant online quotes vary so much between services?
Three reasons. First, each engine assumes different default settings (layer height, infill, wall count) unless you specify them, so they are quietly quoting different prints. Second, slicing algorithms estimate print time differently, and time is the dominant cost. Third, some quotes bury supports, labour and shipping while others itemise them. A quote that looks cheap may simply have deferred those costs to checkout, or assumed a coarser, weaker print than you wanted.
How does 3DCentral quote your custom print?
3DCentral runs a 200+ printer farm in Quebec, so quoting is built around domestic capacity rather than overseas batching. A few things change the math for Canadian buyers specifically:
Because we print and ship inside Canada, your quote is in Canadian dollars with no cross-border customs, brokerage or duty added at delivery, and no currency conversion guesswork. You also approve a preview before anything prints, so the geometry, orientation and support choices that drive the price are confirmed up front, not discovered after.
For custom models you bring your own file. If you don’t have a model yet, our AI-assisted, human-finished generator (dual Tripo + Rodin engines) turns a prompt or photo into a printable starting point that our team refines. The catalog also blends original 3DCentral designs with curated community-artist models, so you get both house creations and licensed favourites.
What about commercial rights to printed designs?
One clarification, because it affects what you can do with a print. 3DCentral’s Commercial License covers original 3DCentral designs only. For your own uploaded custom files you keep your rights, and for community-artist models you want to sell, contact the artist directly for commercial permission. Quoting a print and licensing a design are two separate things.
Ready to see the real numbers on your part? Upload your file or describe your idea and get an itemised, CAD-priced quote you approve before we print on our Quebec on-demand 3D printing service.
Frequently asked questions
Is a 3D print priced by weight or by volume?
Neither alone. Material cost is driven by volume and infill (volume x shell + infill fraction x density), but the full quote also includes machine print time, support waste, post-processing labour and quantity. Weight only approximates the material line, which is often a minority of the total.
Why did I get three different quotes for the same STL file?
Because each service assumes different default settings (layer height, infill, wall count), estimates print time with different slicing algorithms, and itemises or hides supports and labour differently. To compare fairly, specify the same material, infill, layer height and quantity to every service.
Does higher infill always cost more?
Yes, but the trade-off is poor for display pieces. Going from 50% to 100% infill adds roughly 40-60% print time while adding only 10-15% strength. For decorative collectibles, 10-20% infill usually looks identical and keeps your quote lower.
How can I lower the cost of my 3D print?
Choose a lower infill (10-20% is plenty for display pieces), use a coarser layer height like 0.24 mm where fine detail is not critical, orient the model to reduce supports, and order in larger quantities to spread the fixed setup cost. Locking these settings before requesting a quote also lets you compare services fairly.
Do Canadian customers pay customs on 3DCentral prints?
No. 3DCentral prints and ships from its Quebec farm, so orders stay inside Canada with no cross-border customs, brokerage or duties, and pricing is in Canadian dollars with no currency conversion.
Can I sell prints of a design I order from 3DCentral?
It depends on the design. 3DCentral’s commercial license covers original 3DCentral designs only. For your own uploaded files you keep your rights, and for community-artist models you must contact the artist directly for commercial permission.
