Bring the joy of engineering and playtime together this Children's Day! The "Print Together" Modular Toy Train Kit is a fully 3D-printable, interlocking toy designed to be a fun, collaborative project for parents and kids. From the flat print bed to the play table, this kit turns 3D printing into an interactive, hands-on learning experience.

As seen in the project images, the kit transforms seamlessly from a collection of neatly organized, flat-printed parts on the play table into a sturdy, functional toy train.

🎨 Features & Design Highlights
100% Support-Free Design: Every major component—the chassis, boiler, cabin, smokestack, and wheels—has been meticulously optimized to print flat against the build plate. No messy supports or post-processing required!
Smart Interlocking System: Uses a custom peg-and-hole tolerance system. The standard pins and axle pins feature smooth chamfered tips, making it incredibly easy for little hands to press-fit the parts together.
Fully Functional Wheels: Thanks to the dedicated axle-pin design, the wheels spin freely once assembled, letting kids roll their creation across any play track or table.
Vibrant & Customizable: Print each module in a different color (like FireBrick Red, Dodger Blue, and Gold) to create a striking, classic locomotive look.
📋 3D Printing & Assembly Instructions
Choose Your Mode in OpenSCAD:

Set layout_mode = "print_plate" to generate the optimized, flat, ready-to-slice print bed layout.
Set layout_mode = "assembled" to preview how the final locomotive snaps together.
Adjust Slicing Tolerances: The script includes a built-in tolerance variable (default 0.3mm), which is ideal for standard FDM printers. Adjust this slightly if your machine prints tighter or looser joints.
Print Settings:

Infill: 15–20% (Grid or Gyroid for durability).
Walls/Perimeters: 3 for extra strength on the pins and axles.
Material: PLA (Safe, vibrant, and easy to print).
⚠️ Safety Note
Recommended Age: 3+
Note: This kit contains small parts (connecting pins). Parental supervision is highly recommended during assembly—making it the perfect opportunity to build, learn, and print together!
📦 What's Included in the Plate Layout:
1x Engine Chassis (with front cowcatcher)
1x Steam Boiler (with pre-aligned pin holes)
1x Driver's Cabin (with open windows)
1x Flared Smokestack
4x Aesthetic Spoke Wheels
5x Standard Connecting Pins (includes 1 extra spare)
4x Smooth Axle Pins
Happy printing, and good luck to everyone entering the Children's Day Contest! If you love this design, please drop a like and share your makes!