Interesting! Actually my dream would be to make a system deployable by a fleet of drones. Rovers are actually complex to move, especially in an uncontrolled environment with lots of plants.

I don't think any rice farmer would like to put concrete blocks in their fields unless every task is reliably automated: they depend on machines to prepare, plant and harvest the rice and a stone in the middle of a ricefield would make these steps harder.

I know that there are several projects using wirebots for 3d printing. It usually allows for a bigger printing volume than regular CNC-like designs, and I think they must be able to have a high precision too. I am wondering what is the limitation there.