I saw someone posted a full size image of their base. I couldn't find any button that do it, even in devmode. I wander how to do it cause I want to post my own base.

Holding down F9 hides the UI so you can take a screen shot and also adds a screen shot in the your localappdata folder.

I saw someone taking an image of the whole base, not just the screen. Like a zoom-out to see the full grid