STL to 3MF Converter

About

🪝 STL to 3MF Converter: pack your parts into one printable 3MF

Got a folder of loose .stl parts and no clean way to send them to a slicer together? This stl to 3mf converter combines one or several STL files into a single multi-part 3mf project, right in your browser. No upload, no account, no size limit, it all runs client-side.

Most online tools handle only one file at a time. A stl to 3mf converter tool should assemble a real project instead of wrapping a single mesh.

🚀 Quick start:
1. Install the extension with the "Add to Chrome" button
2. Open the side panel or the full-tab workspace
3. Drop your .stl file, a .zip, or a .rar full of parts
4. Get a ready print file, sized and colored, on your build plate

🔟 Reasons to use this stl to 3mf converter tool
1️⃣ Convert stl to 3mf online, fully client-side, nothing ever uploads
2️⃣ Combine multiple STL files into one multi-part 3mf project
3️⃣ Assign a color per part, since plain geometry cannot hold color
4️⃣ Merge every part into a single object for one solid mesh
5️⃣ Split a multi-body model into separate, nameable parts
6️⃣ Hide a part so it stays out of the export without re-importing
7️⃣ See a real build plate: 3D view plus a top-down 2D bed plan
8️⃣ Auto-arrange parts on the bed, or drag them yourself
9️⃣ Rescale inches to millimeters in one click
🔟 Opens in Bambu Studio, PrusaSlicer, and other slicers, private

📦 Combine and pack STL files into one project
➤ Drop several .stl files, or one .zip / .rar archive that holds many, and the converter reads every part inside.
➤ Built for makers who need to combine stl files into a single build instead of exporting one mesh at a time.
➤ Searching how to combine 2 stl files or merge stl files for a print job? Pack them here and download one .3mf instead of juggling loose meshes.
➤ Turn on "combine all parts into one object" for a single fused mesh, per-part colors drop, and you get one clean body.

🎨 Color and identity per part
A plain .stl file is just geometry, it never remembers color. This stl to 3mf converter lets you pick a color for each part, and that color bakes into the output, so your slicer opens with the colors already set.

▸ Give every part its own color before you export.
▸ Rename parts so "part_1" becomes something recognizable.
▸ Hide a part you do not want printed yet, without deleting it.
▸ Add more STL files anytime and keep building the same assembly.

🛠️ Arrange on a real build plate
- Pick a build-plate preset that matches your printer bed.
- Watch the 3D view and the 2D top-down plan update together.
- Auto-arrange packs every part with one click, or drag by hand.
- Overlap and too-large warnings catch mistakes before you slice.
- Center a part on the bed instantly for a clean layout.

📐 Size it right, then preview
Type an exact Width, Depth, or Height and the part scales uniformly. Modeled in inches? One click rescales by 25.4 back to millimeters. Rotate the model, check every angle, and save a .png screenshot before you export.

The 3mf file format bundles mesh, color, materials, and part metadata into one zipped container. What is a 3mf file if not the answer to "3mf vs stl"? A bare .stl stores plain geometry only, which is the real difference between stl and 3mf. Cura and OrcaSlicer favor the 3mf file type for multi-part 3mf 3d print files, sometimes typed as m3f. Convert stl to 3mf and the file opens in any slicer, viewer, or CAD app, alongside amf, obj, or step.

❓ Frequently asked questions

📌 How do I convert stl to 3mf?
💡 Drop your .stl, .zip, or .rar into this stl to 3mf converter, arrange the parts, and click save, your file downloads in seconds.

📌 Can I combine multiple STL files into one 3mf?
💡 Yes. Add as many STL files as you need and this stl to 3mf tool packs them into one multi-part project, or fuses them into one object if you enable combine.

📌 What is a 3mf file, and how is stl vs 3mf different?
💡 A 3mf file is a zipped package that can carry color, materials, and several parts at once. A plain mesh stores none of that, just geometry.

📌 Does the 3mf keep the colors I set?
💡 Yes. Every part color you assign is written into the file, so it is already colored when your slicer opens it.

📌 Is there a size limit, or does anything get uploaded?
💡 No. This tool has no file-size limit and no upload, conversion runs locally, so your files stay private the whole time.

📌 Will the 3mf open in my slicer?
💡 Yes, in every common slicer, since 3mf is an open, standard 3d print format.

📌 Is this stl to 3mf converter free to use?
💡 Yes, free, with no account and no watermark.

🥇 Add this stl to 3mf converter to Chrome and pack your next multi-part print in minutes. Happy printing! 🎉