Small Tutorial for 3d-modelling for Factorio - includes Blender file for train rig

[AlveKatt]

What you need to think about:

Light comes in at a 45 degree angle from the left.
The camera faces 45 degrees down.
Make sure you set the camera to render in an Orthographic perspective. Factorio is 2d, so real perspective sprites just look wonky.
Parent the camera to an object that is set to not render and animate it rotating 360 degrees.
Also parent the light source to said object
Make make sure there is no interpolation, so the distance the camera rotates between frames is constant.

Attached is a Blender file with a rig for making locomotives and wagons that stretch the way the Vanilla locomotives and wagons does depending on angle.
I can't find the post, but I stumbled on an explanation for this, it's a workaround for how the perspective of objects aren't really aligned with the tiles aspect ratio.

Drawback, the file is not made in the latest version of Blender, you might need to use 2.79 to have it work correctly. It might still be useful as a guide for implementing it in later versions of Blender though, and if you do please share it here. https://download.blender.org/release/Blender2.79/

I probably won't update the file for later versions since I already made my locomotive. I might if I find the energy to make the nuclear locomotive and pretty wagons in my head, but don't count on me updating the file for it, I might just keep using 2.79 for the convenience. https://mods.factorio.com/mod/Steam-Locomotive

Model your locomotive or wagon roughly within the guidline mesh I added and rig it to the included armature.
The two extra bones were needed for the steam locomotive so that the smokestack and water intake didn't become an oval with weirdly changing aspect ratios.

Make sure you mark the right render layers and change the output path. The file has a mask layer marked, it was used when rendering the light mask.

When done modelling, press animation to render all the angles. The front needs to point towards y+.

When the rendering is done, use a program like Texturepacker to put the images in sprite sheets. There are also online sprite sheet generators you might use.