3D Printed Lego Duplo Compatible Motorized Locomotive

My son loves his Lego Duplo Intelli train, unfortunately Lego discontinued it. We have a locomotive from Lego Duplo 2933 but the cabin is missing, I wish to make a replacement part to fix it. He also wants to have a locomotive that has light, and runs on challenging layouts. No problem, dad has a 3D printer and computer that can make new one for you.

The locomotive is modelled after the diesel locomotive in LEGO® Duplo Deluxe Train Set with Motor 2933 (1995 - 2004). This particular model also has plenty of space for batteries and other electronics that is ideal for future modification. I plan to make a updated version that can be remotely controlled using Arduino.

Part list:

• TT electric motor with gear box 1
• 3xAA battery holder x 1
• 8x8x13mm 6 Pin DPDT Mini Push Button Self-locking Switch x 1
• M3x30mm screw x 2
• 5mm LED (with 500 ohm resistor) x 1
• M2x10mm self-tapping screw x 10
• M3x46mm steel rod x 1
• 30x2 mm rubber O-ring x 2

All the electric parts are available online. The rubber O-rings are fitted on the drive wheel to increase traction. I bought the rubber O-ring at the local hardware store at plumbing section. The front axle (3mm smooth rod) was salvaged from computer CD-ROM and cut to size. LED head light is optional, drill a 5mm hole at the headlight position for the LED.

All the STL parts are attached, they are also available on Thingiverse, just download the files and print. I printed with PLA, use support for cabin and middle section.

1. Put the rubber o-ring on the drive wheel
2. Mount the drive wheels on the TT motor gearbox axle
3. Mount the TT motor with drive wheels to the lower chassis use 2 M3x30 screws
4. Mount the front wheel assembly and secure it to the lower chassis with the lower axle cover use 2 M2x10 self-tapping screws
5. Wire the switch, battery box and the motor, add LED headlight
6. Install the power switch with cap to the middle section body, use the power switch base and 2 M2x10 self-tapping screws
7. Assemble the middle section to the lower chassis with 6 M2x10 self-tapping screws, fix the cabin to the middle section at hinge.