Video: https://www.youtube.com/watch?v=dkfyw4iPtmQ

I wanted to make my own train set, but instead of starting entirely from scratch, I decided to take advantage of the Ikea Lillabo/Brio track system. I was also inspired by the following projects:

• https://www.thingiverse.com/thing:3553059
• https://www.thingiverse.com/thing:3949927

Like those projects, my engine model uses an electric T motors common in Arduino robot kits. No mounting hardware is needed, just slides into place! Some tabs do need to be trimmed off for it to fit nicely. See the photo for orientation. Just need to put it in motor end first, and then turn axles vertically for it to go in.

The driven wheels of the engine model are grooved so a 1in plumbing O-ring (found at any hardware store) can be used. Additionally, there is space in the "cab" area and at the nose for wheel weights. This gives the engine model some weight, which was required in my testing to make it run well. I store a single cell lipo battery in the "battery car", which has a cover to use these switches to turn the model on and off. While I used the a lipo, you could use a 9v or any battery that will fit! (motor speed will vary on voltage)

The engine model has specific front and rear wheels. All other cars use the same wheel.

Since I dont have an existing Brio or Ikea train set, I printed all my tracks from the following project using a -7.4 mm Z offset in my slicer, so that the tracks were thin (no need to waste filament/time making them thick if I dont have to be compatible):
https://www.thingiverse.com/thing:1938409

Additionally, because I didn't have any cars to be compatible with, my designs use a hitch system (not the magnets like real sets). The cars can link directly, but I was having derailing issues. So I made the "knuckle" model, which adds an extra degree of freedom and made the train run much much more reliability, so I recommend that for every hitch. You can see the knuckle in the caboose photo.

If needed, I dimple over the studs of the wheels and hitches with a hot iron to keep them from falling off, as seen in the caboose photo.

Thats it! Choo Choo!