If you're planning to build a plastic, subscale 80s Toyota Hilux using a 3D printer so you have a sweet ride when you get zapped by a shrink-ray, but have balked at the difficulty of making the drivetrain, boy are you in luck. You can thank Eric Harrell, because he's made a 'working' Toyota 22R-E engine and 4WD transmission. Wow.
And, since it's all just data, you can download all the files you need to print your own, on your own 3D printer, right up there. As you can see in these videos, the engine and transmission turn, the pistons move, you can shift gears, valves open and close, everything. Well, everything except being able to withstand combustion to actually run.
I think the engine is being driven off a small motor in place of the alternator. Maybe you could cast the whole thing in metal and actually make a working engine from it?
This would make a fascinating learning tool, and is a great example of just how excited you should be getting, in your trouser-pants, about 3D printing becoming commonplace.