Hidden Side Latch for 3D Printed Boxes (ready to import STEP file)

Featured in my latest YouTube video:

In this video I compare 3 different locking mechanisms for 3D printed boxes, explain their pros and cons, and show when each one makes the most sense depending on your project.

This hidden side latch is one of those three mechanisms, and in the video I explain how it works, how to install it, and when it is the best choice compared to other systems.

Original design by Salveo:

https://www.youtube.com/@salveo3d

This mechanism is based on Salveo’s original concept. I highly recommend checking his original video and channel.

I used his design as inspiration and remixed it to better fit my own workflow and to make it easier to integrate into custom box projects.

This is a hidden side latch mechanism designed for 3D printed boxes.

Unlike traditional external latches, this system is fully integrated into the wall of the box, creating a very clean and professional look.

The biggest advantage of this mechanism is simple:

it allows you to build boxes with volumetric lids.

That means your lid can have thickness, shape, or internal geometry without being limited by the latch system.

This solves one of the biggest limitations of simpler latch systems.

Instead of using a 3D printed spring, this design uses a 19mm office binder clip as the spring mechanism.

This has some major advantages:

• Much better long-term durability

• No spring fatigue

• No creep over time

• Better tactile response

• More consistent force

The button feels extremely satisfying and professional to use.

One of my favorite things about this system is that the latch sits almost completely flush with the box wall.

This means:

✔ No external bulky parts
✔ Cleaner visual appearance
✔ Better for portable cases
✔ Better for stackable designs

If you combine this with an internal hinge, the entire outside of the box stays clean and rectangular, with no external protrusions.

That makes it one of the cleanest locking systems for custom boxes.

Included files:

1. Hidden Side Latch (STEP)

A reusable CAD-ready latch mechanism you can directly import into Fusion 360 or other CAD software.

Recommended file:
Hidden_Side_Latch_3mm_Parametric.step

Use it as a universal insert for your own custom boxes.

2. Demo Box (STL)

A complete ready-to-print example box with the latch already integrated.

Recommended file:
Hidden_Side_Latch_Demo_Box_3mm_ReadyToPrint.stl

Perfect for testing before integrating it into your own projects.

Best use cases

This mechanism is perfect if:

✔ You want a volumetric lid
✔ You want a hidden locking system
✔ You want a cleaner exterior
✔ You want better spring durability
✔ You want a premium button feel

Tradeoffs:

• Takes internal space inside the box

• Requires a metal clip

• Slightly more assembly than simpler latch systems

That’s why in my video I compare it against other latch systems, because each one solves different problems.

Print settings

Recommended:

• Layer height: 0.2mm

• Walls: 3

• Infill: 15–20%

• Material: PLA / PETG

Additional hardware:

• 1x 19mm office binder clip

Designed in Fusion 360.
Inspired by Salveo.
Remixed and optimized by KNINcustom.
Built for functional prints.