How to Assemble 3D Printed Parts (Without Losing Your Mind)

When it comes to 3D printing, there’s one phrase that comes up again and again: “This part doesn’t fit on my printer bed.”

Far from being a limitation, this type of challenge pushes us to think more strategically: what if we print it in parts and then assemble it?

Splitting a model into sections may seem simple at first, but if you want a final result that’s functional, strong, and visually clean, the assembly needs to be well-planned—starting from the design phase. Here are some key tips to make it work.

1. Before you print: think about the assembly

The magic of assembly starts long before the printer gets to work. From the modeling software, you need to consider how the pieces will fit together.

Will it be a permanent assembly or does it need to come apart later? Should the parts withstand pressure or just snap together?

These decisions will guide which type of joint or bonding method to use.

2. Common Methods for Assembling 3D Printed Parts

There are many ways to connect printed components—and each has its own benefits (and quirks). These are some of the most common:

🔸 Glue: the tried-and-true solution

If you’re working with PLA, PETG, or resin, adhesives can be your best friend.

Cyanoacrylate (aka super glue) works great for small, quick joints. But if you need something more heavy-duty, two-part epoxy adhesives offer stronger bonds.

Just make sure to sand the surfaces lightly before applying the glue for better adhesion.

🔸 Plastic welding for strong, seamless joins

For materials like ABS, acetone is a powerful ally. Applied carefully, it slightly melts the surface, creating a chemical bond between the pieces.

You can also use a soldering iron or a 3D pen to fuse parts with hot filament. It’s a bit more advanced but perfect for strong, glue-free joins.

🔸 Mechanical assemblies: screws, magnets, and snap fits

Want your model to come apart easily? Then mechanical joints are the way to go.

Design clips, tabs, dovetails, or even magnet slots.

Another option: use heated brass inserts or nuts to make your pieces compatible with screws.

This is ideal when your project needs frequent access or disassembly.

3. Practical Tips for a Successful Assembly

Don’t trust the CAD model blindly: What looks perfect on screen may need real-world tweaking. Always print small test pieces to check tolerances before going all in.

Apply pressure while the glue cures: A few clamps or rubber bands can make a huge difference.

Use alignment pins or guides: They help keep everything in place while bonding.

Don’t skip the finishing touches: Sand, fill, and paint the seams to hide them. No one needs to know your model was printed in five parts.

4. When the model is too big for your printer...

If your print far exceeds your printer’s build volume, don’t panic.

Many designers break down their models into modules with puzzle-like connectors or LEGO-style joints.

You can also add internal channels for rods or supports—like a skeleton—adding stability to the entire structure.

Final Thoughts: Assembly is Part of the Design Process

Rather than being a backup plan, assembling 3D printed parts is an opportunity to flex both creativity and technical skills.

When done right, the seams are invisible—and the final result is just as good (if not better) than printing it all in one piece.

At M Aerospace RTC, we specialize in 3D printing solutions for complex, large-scale, and industrial projects.

From design engineering to final assembly, we help you take your idea to the next level.

Get in touch with us—and let’s bring your project to life.