Rajesh's team asks about building something to help support a Stack of Building Units delivered to a circle for Mission 12, and leaving that support object in the circle.
I don't recommend doing that. For Mission 12, the Height scoring condition (like most of the City Shaper Missions) requires that a stack be Independent in order to score.
"HEIGHT - If there are Independent Stacks at least partly in any Circles, add all of their heights together"
Rule 33 says that Independent means "Not touching any equipment," and Rule 02 says that Equipment is "anything you bring to a Match for Mission-related activity."
So, if the Robot leaves some support Equipment in the Circle and touching a Stack to stabilize it, then that Stack will not earn points for Mission 12.