How to 3D print from your iPhone

The phone is already at the printer

The laptop is in another room, but the phone is in your pocket when the part breaks, when a friend sends you a model, or when you find exactly the bracket you need on Printables. Printing it takes three things: the model, a slicer that turns it into G-code for your printer, and a way to get that G-code to the printer. An iPhone can do all three, as long as the slicer runs in the browser: OrcaSlicer, PrusaSlicer, Cura and Bambu Studio are desktop programs with no iPhone version.

Step 1: save the model to Files

The online slicer takes an STL or 3MF of up to 50 MB from the Files app.

• Downloaded in Safari: it is in Downloads in Files (in iCloud Drive or on the iPhone, depending on Safari's download setting). The download arrow in Safari's toolbar opens it.
• Received by message, AirDrop or e-mail: open it, tap Share, then Save to Files. AirDrop from a Mac usually offers to save to Files directly.
• In a cloud folder: Google Drive, Dropbox and OneDrive appear in Files when their app is installed and turned on as a location.

Step 2: slice it in Safari

1. Open the online slicer in Safari and sign in, or create an account (free, no card).
2. Tap Choose a file and browse to the model. iOS may offer the photo library and the camera first; choose the option to browse files.
3. The model opens in 3D. Turn it with a finger: is it the right part, right side up, at a plausible size?
4. Pick your printer's Brand, Model and Nozzle among 380+ printers. It is saved on your account, so the next print starts here.
5. Choose the Print profile and the Material. For a first print, leave Supports and Adhesion on Auto.
6. Tap Slice and download.

The slicing runs on the server, with the unmodified OrcaSlicer and your printer's own profile, so an older iPhone gets its file as quickly as a new one. The page reports the print time, the filament in grams and meters and the number of layers. If the print is longer than you want, pick a coarser print profile or lower the infill and slice again: the same file re-sliced within 10 minutes spends nothing.

Step 3: check the file name

The G-code lands in the same Downloads folder in Files. A .gcode file suits most printers; Bambu Lab printers get a .gcode.3mf. If the name changed on the way (a number appended, the extension cut), touch and hold the file and rename it. Short names are easier to find on a printer's screen.

Step 4: get it to the printer

The printer's web page: usually the shortest route from a phone

Klipper printers run Mainsail or Fluidd, OctoPrint turns a small computer connected to the printer into an upload page, and networked Prusa printers have PrusaLink. With the phone on the same Wi-Fi:

1. Find the printer's IP address on its screen or in your router's device list.
2. Open it in Safari. Add it to your home screen if you print often.
3. Tap upload, choose the G-code from Files, and start the print.

SD card or USB stick

iPhones with a USB-C port (iPhone 15 and later) read a USB-C card reader or stick. Older iPhones with a Lightning port need an adapter, such as Apple's Lightning to SD card reader. The card appears under Locations in Files: copy the G-code onto it, wait for the copy to finish, and move the card to the printer.

The printer maker's app

Some printer makers' apps accept a file from the Share sheet in Files. For Bambu Lab printers, Bambu Handy monitors prints and starts them; whether it can send a .gcode.3mf from your phone's storage depends on the app version, so try it once with a small file. The microSD card works on every Bambu Lab printer that has a card slot. The .gcode.3mf explained covers the Bambu routes.

What to expect from a phone

• Nothing to install. The slicer is a web page. Safari and Chrome for iPhone both work.
• A small screen for settings. The settings stack under the 3D view. The ones that matter for most parts are few: layer height, material, infill, walls and supports. Which settings matter for a functional part explains each.
• Not the whole desktop slicer. No colour painting, modifiers, custom start G-code or toolpath preview. For those, a desktop slicer on a computer remains the tool.
• A connection. Slicing happens on the server, so the phone needs a data connection while it slices.

When something goes wrong

• The printer's screen does not list the file. Check the ending (.gcode, or .gcode.3mf for Bambu Lab) and that it is at the top level of the card rather than in a folder the printer does not open.
• The model is tiny or huge in the preview. The STL was probably exported in inches or in metres. The slicer does not rescale models, so export it again in millimetres where it came from.
• The web page of the printer does not load. The phone must be on the same Wi-Fi as the printer, not on mobile data or a guest network.
• The model does not fit. The preview warns when a model is larger than the printer's bed; scale it where it was made, or pick the right printer.

What it costs

The online slicer gives every account 1 free slice, its first (a free account, no card). After that, a slice uses one slice from a Slicer pack (20 slices for $3, once, never expire) or 5 credits, and slicing is included in Pro and Unlimited. Re-slicing the same file with other settings within 10 minutes is free. To know how long a print will take and how much filament it needs before you slice, the print time and cost calculator works without an account.

The short version

Save the model to Files, slice it in Safari, and upload the G-code on the printer's web page or copy it to the card. Slicer for iPhone keeps the steps on one page; open the online slicer and try it with the file you have.