I assume that my readers are in intermediate or higher level in designing in Tinkercad. If you are beginner in Tinkercad, please click here. In this tiny challenge, I have challenged myself to make a mini locomotive train using 3D print. Here is my model:

https://www.tinkercad.com/things/eGFpmQvdx0U

Supplies

1x 3D printer

1x PLA blue filament (it is for the locomotive and you can choose what you desire)

1x PLA black filament (it is for the base of the locomotive)

1x PLA gold filament (it is for the railroad and you can choose what you desire)

Tinkercad

1x Hot Glue

1x Dremel Digilab 3D Slicer

1x Scrapper

Step 1: Preparation Using Tinkercad

First, open the Tinkercad. You will get an empty workspace. Rename it with the name as you desire. In this case, I rename it with "Mini Locomotive". After that, change the grid property, so the workplane fits as you 3D printer. Because I have Dremel 3D40 3D Printer, I choose "Dremel 3D40/ 3D45". For the units, you can choose between millimeters or inches. I choose millimeters because it is more accurate and easier. Then, click "Update Grid".

Step 2: Base of Coal Car

First, start making the base of the coal car. Drag a box into the work plane and change the color into black. Change the length to 97.22 mm and width to 45.83 mm. Also, the height is 5.56 mm.

Step 3: The Cover of Coal Car

Drag 2 boxes into the workplane. Make the first box into dimension length of 95.83 mm, height of 27.78 mm, and width of 44.74 mm. Make a hole using second box by clicking hole in the top right corner. Change the color into green. Make bevel in each corner using metafillet. See the picture.

Drag another 2 boxes into the workplane. It is for making the wall of the car higher. See the picture. Group all of them together.

Step 4: The Wheels of the Coal Car Base-Pt.1

Drag another box into the workplane. Scale the box into the length of 34.72 mm, the width of 28.06 mm, and the height of 11.11 mm. Set aside.

Step 5: The Wheels of the Coal Car Base-Pt.2

Drag a cylinder into the workplane. Scale it into 11.11 mm on all sides. Duplicate the cylinder and then scale it into the length of 2.50 mm, width of 9.72 mm, and the height of 9.72 mm. Move it to the end of the other cylinder.

Step 6: The Wheels of the Coal Car Base-Pt.3

Drag and move the cylinder into the box for the wheel until the bigger cylinder is just 2 mm out of the box. Then group them together. Make it into 4 cylinders to becoming 4 wheels. Drag and move the other wheels into the base as same as previous. Group the box with the wheels.

Step 7: The Wheels of the Coal Car Base-Pt.4

Next drag the "Ball" in the "Connectors" tab. Note that the all of the object in the "Connectors" tab are "Scaling Locked", so you cannot change the scale.

Align the ball with the box. Select the middle button to align the ball centrally with the box. Group all together. Duplicate the box and rotate them 180 degrees. Move the duplicated object about 60 mm away each other.

Step 8: Coal - Pt. 1

Grab a box. Scale it into the length of 33.81 mm, the width of 81.94 mm, and the height of 16.79 mm.

Step 9: Coal - Pt. 2

Go the "Shape Generators" folder. Select "All". At the end of the page, search for "Terrain". Click "Workplane" button at the top right corner. Click it to the top of the box. Select the terrain button and press the button "D" on your keyboard, so that the terrain has the same height with the box. Change the color to black as it is for a coal. Play around with the shape generator to make it look like coal. You can choose the option of terrain as you desire. I choose "Randomizer" to 512, "Smoothness" to 10, and "# Of Division" to 30. Align the terrain with the box. Duplicate it. Put it side by side with the first terrain.

Step 10: Coal - Pt. 3

Arrange the height of the terrain. The height of the first terrain is 7.75 mm and the second terrain is 15.5 mm.

Attach it with the wheel that you already made in previous step.

Step 11: Preparing to 3D Print

Export the Coal car into 2 parts because they have different color. Select the .stl files and save it to your computer. For I have Dremel 3D Printer 3D40, I have downloaded the Dremel Digilab slicer software. Click here to download it. Choose the right option for your computer.

Prepare the filament and put it into the 3D printer. Choose the color what you like. In this case, I choose 2 colors. The black is for the base and the coal. Blue is for the cover of the coal car. Level it before printing. Open Dremel Digilab Slicer and open the .stl file that you want to print. Then, select the option for printing. For material, select "PLA". For profile, it is up to you to choose. To have a very good print, choose high quality, but it take a very long to print. I choose medium quality to print and the printing result is already excellent. For other options, I choose the recommended setting. To know further about this option, click here. Lastly, save the slicer to your computer or you can just print it over your network connection to your printer. The printer is printing your design, just wait it.

Step 12: Finished Coal Car

Put glue using hot glue and stick it to the coal car. See the picture.

Step 13: The Locomotive Base - Pt. 1

Drag and move the cylinder into the box for the wheel until the bigger cylinder is just 2 mm out of the box. See the picture for the measurement. Then group them together. Make it into 6 cylinders to becoming 6 wheels. Drag and move the other wheels into the base as same as previous. Group the box with the wheels.

Step 14: The Locomotive Base - Pt. 2

Drag the box into the workplane. The length is 8 mm and the width is 15.42 mm.

Step 15:

Make hole on the top of the box. See the picture for more clarification. Group them together, so the result is that the box has some levels on the top of it.

Step 16:

Using some boxes, create a list and bumper of the locomotive. For more details, look closely in the pictures.

Step 17:

Create 4 small wheels in front of the locomotive by dragging the cylinder into the workplane. You will need 2 cylinders to create 1 wheel. For the dimension, see the picture. Do not forget to group them together and then copy them to make 4 wheels.

Step 18:

Next, make train's hook. Click the connector tab and select socket. Change the color to black.

Step 19: The Locomotive Top

Drag 3 cylinders to workplane. Change color into black. Make the cylinders into the measurement as shown in the picture. The smallest cylinder put into the bigger one. Rotate the third cylinder to 90 degrees and makes a hole in it. Group them together.

Step 20: Valve Gear

To make the valve gear, drag 5 cylinders into the workplane. Make all the diameter of the cylinders of 4 mm. Drag 2 boxes into the workplane and attach them to the previous cylinders. Group them together. Change all colors into black.

Print it to 3D printer.

Step 21: Boiler of Locomotive

Drag Round Roof into the workplane. Change the measurement with the length of 51.57 mm and the width of 18 mm. Drag 2 cylinders into the workplane. Put them into the round roof. The sizes of the cylinders are shown in the picture. Group them together and change the color into blue.

Step 22: Cab of the Locomotive

Drag 6 boxes to the workplane. The 4 of them become hole. From the two of them, make the length and height of 9 mm each. For the measurement of the others, see the pictures. Group them together and make the color blue. Print it to 3D Printer.

Step 23: Rail

To make rails of train, drag a box to the workplane. Make the length of the rail 2 mm, width of 41mm, and height of 1 mm. Duplicate them. Set them apart 18 mm. Do the same with others until there are 14 bars of them. Drag another box. Make the length of it 3.80 mm, width of 240 mm, and height of 2.80 mm. Duplicate the box and make the length of 2 mm, height of 1.80 mm. Make it a hole. Then group them together. Duplicate it into 2. Flip them horizontally. Move them 38.20 mm apart.

Print it to 3D printer.