Calculator
How to use the 3D printing cost calculator (and find out if the part makes a profit)
Learn how to use the STL Prime 3D printing cost calculator: material, energy, machine-hour, failures, finishing and what's left on your own store, Etsy, eBay and Amazon Handmade.
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News
The 10 free models are out; the catalog opens November 20
The ten free models and the e-book are unlocked in your account area as soon as you sign up. The full STL Prime catalog and subscriptions open on Friday, November 20, 2026.
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Guide
Commercial STL license: what you can sell (and what you can't)
The file and the part are different things. What a commercial STL license allows, how to read Creative Commons (BY, SA, NC, ND), the catch with brands and characters, and how the STL Prime license works.
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Sales
How to price a 3D printed part: from cost to selling price
Markup or margin, break-even price, channel fees, shipping, tax, failures and profit per printer hour: the method to go from cost to a price that actually adds up.
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Guide
STL, 3MF or STEP: which file to download for your 3D printer
The practical difference between STL, 3MF, STEP and OBJ: what each format stores, when to use each one, what to check in a 3MF's print profile and which to download in each situation.
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Guide
PLA, PETG or ABS: which filament to use for parts you sell
PLA, PETG or ABS for sellers: strength, heat, finish, difficulty and the real cost of each filament, with a worked example and a guide by type of part.
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Sales
How to photograph a 3D printed part with your phone
Listing photos of a 3D printed part with nothing but a phone and a window: light, background, camera settings, the shot sequence, scale, the part in use and a checklist.
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Guide
Common 3D printing failures and how to avoid them when you sell
First layer, warping, stringing, layer shifts and clogs: the symptom, cause and prevention of each failure, plus the routine of people who can't afford to lose a part.
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Sales
How to pack and ship a 3D printed part without breakage and without paying to ship air
Box, void fill, protecting fragile parts, dimensional weight, postal service or courier, and what to do when a part comes back: the practical shipping guide for people who sell 3D prints.
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Guide
When to buy a second 3D printer (and how to know if it will pay for itself)
The signs that one machine has become a bottleneck, a worked example of how long a second printer takes to pay for itself, and how to organize the queue of a small print farm.
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Platform
What STL Prime does differently — and what's coming
Farm-tested files, a 360° spin before you download, a commercial license on every model and a free cost calculator. And what's on the roadmap: customizing the part right on the platform, with gear and shaft generators.
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Costs
How much does 3D printing cost? The full math, with two examples
Material, energy, machine-hour, failures, finishing and packaging: the real cost of a 3D printed part, with two worked examples and what each item weighs.
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Sales
What to sell 3D printed: how to pick the right part
Not every beautiful part sells, and not every part that sells makes a profit. The six criteria for choosing what to print and sell, the categories that move, and the three-number test.
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Tools
Apps and tools that help people who print and sell
Apps for 3D printing and tools for selling 3D prints: slicers, modeling, monitoring, photos, listings, shipping and order management. What to use at each stage.
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Curation
STL Prime curation: how we pick the STL that turns a profit
How we curate the STL files on STL Prime: market trends, a profitability filter and testing, so you print parts that sell.
Read ›Free e-book: How to start selling with your 3D printer
From choosing the part to your first listing: cost, price, photos and the file license, in the words of people who print.
Topics
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