Karel the Robot.

o: Forgot to put it in the code box; it was indented when I pasted.

Is it better now? I moved the turnLeft to the nextColumn.

 Spoiler

Code:

import stanford.karel.*;

public class StoneMasonKarel extends SuperKarel {

    public void run() {
        while(frontIsClear()) {
            turnLeft();
            while(frontIsClear()) {
                fixWall();
                }
            if(noBeepersPresent()) {
                putBeeper();
                }
            goBack();
            nextColumn();
        }
        turnLeft();
        while(frontIsClear()) {
            fixWall();
            if(noBeepersPresent()) {
                putBeeper();}}
        goBack();
        turnLeft();
                    
    }
    

private void fixWall() {
    while(frontIsClear()) {    
    if(beepersPresent()) {
        move();
    } else {putBeeper();
    }
    }
}

private void goBack() {
    turnAround();
    while(frontIsClear()) {
        move();
        }
    }
        

private void nextColumn() {
    turnLeft();
    for(int i=0;i<4;i++) {
        move();
        }
        }
    
}

Yeah, I'm saving the harder stuff for later and just going to follow the class now. The class learns Karel first, then eventually transitions to Java (I haven't gotten there yet). I'm still trying to figure out how to make 3 work x___X