3D Printable Modular Gear Train Kit (MechaPrint) – Build Your Own Mechanisms

Build Your Own 3D Printed Gear Trains

VIDEO:

This is a modular 3D printable system designed to let you build your own gear trains and mechanical mechanisms using a collection of ready-to-print components.

No CAD work is required.

Choose the gears and components you need, print them, assemble everything and start experimenting.

The system includes different gear sizes, supports, vertical spacers, locks, couplers, cranks, stabilizers and a modular base. All of these components are designed to work together, allowing you to create many different gear arrangements from the same collection of parts.

And if you don't know where to start, I've also included a Starter Gear Train Kit in STL format that you can print and assemble directly to understand how the system works.

How It Works

The entire system is built around the Modular Base.

The base contains multiple slots and mounting positions where you can install the different supports and components.

From there, you can position your gears, adjust their height using spacers, reinforce the structure with stabilizers and combine different gear sizes to create your own gear trains.

Most components are designed to simply fit together.

Small pieces of standard 3D printer filament can be inserted through the corresponding holes to lock certain components in position.

TIP: If the filament passes through the hole too easily, slightly bend the piece of filament before inserting it. This creates additional friction and helps keep the connection securely in place.

This allows most mechanisms to be assembled without screws or additional hardware.

Included Parts

Modular Base

The Modular Base is the foundation of the entire system.

It contains multiple slots and mounting positions where the gear supports and other components can be installed.

By changing the position of the supports, you can experiment with different gear arrangements without having to design a completely new structure every time.

Gears

The system includes four different gear sizes:

• Gear 10mm

• Gear 20mm

• Gear 30mm

• Gear 40mm

Each size is available in two versions.

Standard Gear

The standard version is a normal gear without an external coupling.

Use this version when the gear only needs to transmit movement to another gear.

Included files:

• Gear 10mm

• Gear 20mm

• Gear 30mm

• Gear 40mm

Gear – Coupling

The coupling version includes a connection point on one side of the gear.

This allows you to transfer the rotation of the gear to another component using the included Coupler.

Included files:

• Gear 10mm - Coupling

• Gear 20mm - Coupling

• Gear 30mm - Coupling

• Gear 40mm - Coupling

This is useful whenever you want to take the rotational movement from your gear train and use it to drive another component.

Coupler

The Coupler is the small intermediate component used to connect a Gear - Coupling to another part of your mechanism.

The coupling version of each gear includes a dedicated socket where the Coupler fits.

The Coupler acts as the mechanical connection between the gear and the next component, transferring the rotation from one to the other.

For example, you can use it to connect a gear to the included Crank.

This also makes it easier to design your own components and connect them to the modular gear system.

Crank

The Crank allows you to manually rotate the gear train.

Connect it to a compatible gear using the Coupler, and you can turn the mechanism by hand.

This makes it particularly useful for testing your gear trains, demonstrating different gear ratios and understanding how the complete mechanism works.

Support

The Support is the main structural component used to hold the gears.

Supports are installed onto the Modular Base and provide the structure where the gear shafts are positioned.

Two supports can be positioned around a gear to hold its shaft and create the basic gear assembly.

They can also be combined with Vertical Spacers and other components to create more complex mechanisms.

Vertical Spacer

The Vertical Spacer allows you to change the vertical position of your gears and supports.

If you need one gear to operate at a different height, simply add one or more Vertical Spacers to the assembly.

Multiple spacers can be stacked together, allowing you to create gear trains operating at different levels.

Support Lock

The Support Lock is used to close the upper section of the Support and keep the assembly securely in position.

It can be easily installed or removed whenever you want to modify your mechanism.

Support Lock Spacer

The Support Lock Spacer combines two functions in a single component.

It locks the current support assembly while also providing an additional vertical extension.

This allows you to secure one level of your mechanism while continuing to build vertically above it.

It is particularly useful when creating multi-level or more complex gear trains.

Lateral Stabilizer

The Lateral Stabilizer connects the two support pillars around a gear.

Its purpose is to increase the rigidity of the assembly and prevent the two supports from flexing or moving relative to each other.

This helps keep the gear properly aligned and creates a stronger overall structure.

Gear Spacing Stabilizers

The Gear Spacing Stabilizers connect the supports of different gear assemblies.

Their purpose is to maintain a fixed and rigid distance between different gears.

This prevents the supports from moving relative to each other and helps keep the gears properly positioned and meshed.

Four different lengths are included:

• Gear Spacing Stabilizer 20mm

• Gear Spacing Stabilizer 30mm

• Gear Spacing Stabilizer 40mm

• Gear Spacing Stabilizer 50mm

Choose the appropriate length depending on the configuration of your mechanism.

Starter Gear Train Kit

Not sure where to start?

I've also included a small Starter Gear Train Kit in STL format.

Unlike the individual STEP components, this example is designed to be downloaded, printed and assembled directly.

You don't need to select parts or design your own configuration first.

Simply print the included STL files and assemble the mechanism.

The Starter Kit includes a simple gear train together with two cranks, allowing you to manually operate the mechanism and immediately see how the modular system works.

It's the easiest way to understand:

• How the supports are assembled

• How the gears are mounted

• How the gears mesh together

• How the Coupler works

• How the Crank connects to the system

• How rotation is transmitted through the gear train

Once you understand the Starter Kit, you can use the individual modular components to build your own configurations.

Included Files

Modular System – STEP Files

Base

• Modular Base

Standard Gears

• Gear 10mm

• Gear 20mm

• Gear 30mm

• Gear 40mm

Gears with Coupling

• Gear 10mm - Coupling

• Gear 20mm - Coupling

• Gear 30mm - Coupling

• Gear 40mm - Coupling

Coupling & Manual Input

• Coupler

• Crank

Supports & Vertical Components

• Support

• Vertical Spacer

• Support Lock

• Support Lock Spacer

Stabilizers

• Lateral Stabilizer

• Gear Spacing Stabilizer 20mm

• Gear Spacing Stabilizer 30mm

• Gear Spacing Stabilizer 40mm

• Gear Spacing Stabilizer 50mm

Starter Gear Train Kit – STL Files

A separate set of ready-to-print STL files is included so you can build a complete example mechanism and understand how the system works before creating your own gear trains.

Just slice, print and assemble.

Build Your Own Mechanisms

The idea behind this project is simple:

Choose your gears → Position your supports → Adjust the height → Stabilize the structure → Connect your output → Build your mechanism.

Instead of designing every mechanical component from scratch, you can use these modular pieces to quickly experiment with different configurations.

You can build simple two-gear systems or combine multiple gears, heights, supports and stabilizers to create much more complex gear trains.

The Coupler also gives you a simple way to take the rotation from the gear train and connect it to another component.

When you're finished, take everything apart and reuse the same components for your next mechanism.

What Can You Use It For?

This system is particularly useful for:

• Building custom gear trains

• Experimenting with different gear ratios

• Learning how gears and mechanical transmissions work

• Mechanical prototyping

• STEM and educational projects

• Testing mechanical concepts

• Creating proof-of-concept mechanisms

• Learning mechanical design

• Experimenting with multi-level gear systems

• Building manually operated mechanisms

STEP Files Included

The individual modular components are provided as STEP files.

You don't need to modify them to use the system. Simply import the files into your slicer, print the components you need and assemble your mechanism.

However, providing the STEP geometry also means you can easily import the parts into Fusion 360 or another CAD program if you want to modify them, create your own components or integrate the system into a larger project.

The Starter Gear Train Kit is also provided separately in STL format so you can simply download, slice, print and assemble it.

Assembly

The system has been designed to make assembly as simple as possible.

Components are primarily connected through their integrated fitting features.

For the small locking pins, use short pieces of standard 3D printer filament.

Insert the filament through the corresponding holes to secure the components.

TIP: If the filament fits too loosely, slightly bend it before inserting it. The small bend creates additional friction inside the hole and helps keep everything securely in place.

Print, Build, Experiment

The goal of this project is to make experimenting with gears and mechanical systems easier.

You don't need to design an entire structure every time you want to test a different gear ratio or mechanical configuration.

If you're new to the system, start with the Starter Gear Train Kit.

Then use the individual modular components to create your own mechanisms.

Print a collection of parts once and reuse them again and again to build different configurations.

Print it. Build it. Take it apart. Build something different.

Questions & Suggestions

If you have any questions about the assembly, you're not sure which component to use, or you have an idea for another useful part that could be added to the system, leave a comment here on Printables.

I may continue expanding the kit with additional gears, connectors, supports and other modular mechanical components.