What file should I send a 3D printing service?

Send STEP if your CAD can export it. STEP preserves exact geometry, units, and features, so the service can prepare it for the right process. STL is widely accepted but stores mesh geometry only and carries no units, so the service can't tell millimeters from inches unless you say. When in doubt, send both and tell them which one is authoritative.

FDM, SLA, or SLS: which should I choose?

Choose FDM for cheap, fast form-and-fit checks and larger parts. Choose SLA for fine detail and smooth surfaces on small, precise parts. Choose SLS for functional parts that need strength without support structures, and for small batches. The right pick depends on what the print has to prove: how it looks, how it fits, or how it works.

How much does a 3D printed prototype cost?

Price tracks the process, the material, the part's size and orientation, the quantity, and any finishing. FDM is usually cheapest per part; SLA sits in the middle; SLS and metal cost more per unit but drop sharply with quantity because parts share a build. There's no single number, which is why services give an instant quote from your file.

3D Printing Prototype Service: How It Works

Updated November 13, 2026

A 3D printing prototype service turns your CAD file into a physical part and ships it to you, usually in a few days. You don't need to own a printer or know every process. This guide explains how these services work, which process and file to send, what drives the price and lead time, and when a service beats buying your own printer.

What a 3D printing service does

3D printing prototype service: a shop (online or local) that takes your 3D model, prints it on an industrial machine in the process and material you pick, finishes it, and ships you the part. Most give an instant price when you upload the file.

The appeal is simple: you get a professional-grade part without owning the machine, learning the process, or babysitting a print. You upload a CAD file, choose a process and material, and the quote updates in real time as you change options. That makes a service a fast way to put a prototype in your hand early, when the point is to model, print, learn, and adjust as quickly as possible.

The three processes to know

Nearly every plastic prototype comes off one of three processes. Pick by what the print has to prove.

Process	Strengths	Best for
FDM (melted filament, layer by layer)	Low cost, fast, wide material choice	Form and fit checks, larger parts, jigs
SLA (resin cured with light)	Fine detail, smooth surface	Small precise parts, visual models, masters
SLS (nylon powder fused by laser)	Strong functional parts, no supports needed	Snap fits, housings, short runs, complex shapes

A rule of thumb: FDM for cheap functional checks, SLA when it has to look and measure precisely, SLS when it has to work and take a load. Remember that a print proves geometry and fit, not how the final production material will behave.

Which file to send

The file you upload matters more than beginners expect:

STEP is the one to send if your CAD can export it. It preserves exact geometry, units, and features, so the service can re-prepare it cleanly for the chosen process.
STL is the most widely accepted format but stores surface mesh only. It carries no units, so a shop can't tell millimeters from inches unless you tell them. Fine for simple or organic shapes.
3MF carries units, material, and orientation, and is increasingly accepted.

If you're unsure, send STEP and STL together and say which is authoritative. Before you upload, confirm the model is watertight (no holes or flipped faces) and that the units are right, because a clean file prevents most delays.

What drives the price

A quote is built from a handful of levers:

Process. FDM is usually cheapest per part; SLA is in the middle; SLS and metal cost more per unit but fall sharply with quantity because parts share one build.
Material. Commodity plastics like PLA and PETG are cheapest; engineering grades like nylon and polycarbonate cost more; metal is the most expensive by far.
Size and orientation. Price tracks the bounding box plus support structure, not just solid volume, so a tall thin part can cost more than a compact one.
Quantity. Ten small parts often cost far less each than one, because setup and machine time spread across the batch.
Finishing. Support removal is often included; sanding, smoothing, dyeing, and painting are line items.

Lead time, honestly

Turnaround depends on the queue, the process, and finishing, not just print speed. Simple FDM parts can ship in one to three business days; SLA often two to four; SLS three to five; metal five to ten. The clock usually starts when the file is approved, so a messy file that needs back-and-forth is the most common cause of a slow job. Rush scheduling is the biggest add-on.

Service or your own printer?

A cheap desktop FDM printer is a fine first tool for rough, fast loops, and owning one lets you iterate for the cost of filament. Use a service when you need a process or material you can't run at home (SLA detail, SLS strength, metal), when the part has to look or measure to a higher standard, or when speed and reliability matter more than tinkering. Many founders do both: rough iterations on a desktop printer, then a service for the parts that have to be right.

The short version

A 3D printing prototype service prints your file and ships a part. Send STEP when you can, pick FDM, SLA, or SLS by what the print must prove, and expect the price to track process, material, size, quantity, and finishing. It's the fastest way to feed the prototype loop before you commit to production and tooling.

Working on your own product? The idea-to-shelf program is the step-by-step system behind these guides, from idea and prototype through manufacturing and launch.

Frequently asked questions

What file should I send a 3D printing service?: Send STEP if your CAD can export it. STEP preserves exact geometry, units, and features, so the service can prepare it for the right process. STL is widely accepted but stores mesh geometry only and carries no units, so the service can't tell millimeters from inches unless you say. When in doubt, send both and tell them which one is authoritative.
FDM, SLA, or SLS: which should I choose?: Choose FDM for cheap, fast form-and-fit checks and larger parts. Choose SLA for fine detail and smooth surfaces on small, precise parts. Choose SLS for functional parts that need strength without support structures, and for small batches. The right pick depends on what the print has to prove: how it looks, how it fits, or how it works.
How much does a 3D printed prototype cost?: Price tracks the process, the material, the part's size and orientation, the quantity, and any finishing. FDM is usually cheapest per part; SLA sits in the middle; SLS and metal cost more per unit but drop sharply with quantity because parts share a build. There's no single number, which is why services give an instant quote from your file.
How long does a 3D printed prototype take?: A simple FDM part can ship in one to three business days. SLA is often two to four days, SLS three to five, and metal five to ten. The clock usually starts when the file is approved, not when you upload it, and rush options cost more. A clean, watertight file with correct units prevents most delays.

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