I want to change a doodad's color via triggers. How do?
(The doodad is "Force Field Wall" if you are curious. I'd like it to either stay blue as it is, or to be set to look red.)

I believe there is a "Set tint" (or something similar) action to do that.

EDIT:
Wait, crap, that may just be for units/buildings. If you need it to be changed via triggers, you could theoretically make the doodad into an unselectable unit.

Then, can you tell me how to make an unselectable unit with a doodad's image?

Create a unit, set the unit's actor to the same actor the doodad uses, and then set the unit's flags to "Unselectable", "Untargetable", "Invulnerable".

There's a 'send actor message' trigger action that can be used to send tinting/etc messages to any actor, unit or doodad.

If it is preplaced, you should be able to tint it in the preplaced doodad's properties.

If you want to tint it more dynamically, you need to send an actor message to the doodad.

If you want to tint all of these doodads from map's start, you can add the following into actor events:
ActorCreation -> Set Tint Color

Any more details on that? How would I create the said message?
The thing is, I have 2 times the same doodad representing goals. I want one to stay blue since it represents Blue Team's goals, while I'd like the other one to look Red. The message method would only change one doodad's tint, right?
Because I must switch the color of the doodads at some point in the game (teams switch side, and thus their goals should switch colors too).

As long as you just tint the doodad and not the doodad's actor, it wont affect both.

Only one object will be affected, IIRC it's pretty intuitive to use it, you just pick Send Actor Message then mess with the parameters:
- target actor: Actor From Doodad -> Value, then it lets you pick the doodad from the terrain editor, or you can use a Doodad variable (initialized at map start with your doodad)
- message: you can pick Value or Function here, Value gives you the same interface as the data editor, Function means you can use trigger variables as actor message parameters (useful)

Worked perfectly. Thank you.