Paint

[techno_letsgo]

This suggestion is purely cosmetic, the ability to paint. To make a machine look blue, to make an inserter look red, basically that stuff. It could be used to organize things better, or just to make the factory a bit more colorful. When you paint once, a small tint of that color will go on the object. You can make it darker by painting more on the same object.

[daniel34]

While I like the idea of making the factory more colorful, I don't think this should be implemented in the base game. The nice thing about the current coloring is that you instantly know what entity is it based on it's color, when you watch screenshots or videos for example. If the inserter is blue, it's faster than the yellow one. Red inserters transport over 2 tiles. The same applies to belts and assemblers. You can instantly see what type they are just by looking at their color.

There are already some mods that allow you to color your factory the way you want it. The Color Coding mod adds different colors for concrete, trains and lamps, and they look very good from the screenshots.