io.write("Cube height? (top to bottom):")                                                                                                                  
  local height = tonumber(io.read())                                                                                                                         
                                                                                                                                                             
  io.write("Cube width? (left to right):")                                                                                                                   
  local width = tonumber(io.read())                                                                                                                          
                                                                                                                                                             
  io.write("Cube depth? (front to back):")                                                                                                                   
  local depth = tonumber(io.read())                                                                                                                          
                                                                                                                                                             
  io.write("Dig direction? (up/down):")                                                                                                                      
  local dir = io.read()                                                                                                                                      
                                                                                                                                                             
  local digVert, moveVert, digBack, moveBack                                                                                                                 
  if dir == "up" then                                                                                                                                        
    digVert = turtle.digUp                                                                                                                                   
    moveVert = turtle.up                                                                                                                                     
    digBack = turtle.digDown                                                                                                                                 
    moveBack = turtle.down                                                                                                                                   
  else                                                                                                                                                       
    digVert = turtle.digDown                                                                                                                                 
    moveVert = turtle.down                                                                                                                                   
    digBack = turtle.digUp                                                                                                                                   
    moveBack = turtle.up                                                                                                                                     
  end                                                                                                                                                        
                                                                                                                                                             
  for d = 1, depth do                                                                                                                                        
    turtle.refuel(1)                                                                                                                                         
    turtle.turnLeft()                                                                                                                                        
                                                                                                                                                             
    local goingUp = true                                                                                                                                     
                                                                                                                                                             
    for w = 1, width do                                                                                                                                      
      turtle.dig()                                                                                                                                           
      turtle.forward()                                                                                                                                       
                                                                                                                                                             
      if goingUp then                                                                                                                                        
        for h = 1, height - 1 do                                                                                                                             
          digVert()                                                                                                                                          
          moveVert()                                                                                                                                         
        end                                                                                                                                                  
      else                                                                                                                                                   
        for h = 1, height - 1 do                                                                                                                             
          digBack()                                                                                                                                          
          moveBack()                                                                                                                                         
        end                                                                                                                                                  
      end                                                                                                                                                    
                                                                                                                                                             
      goingUp = not goingUp                                                                                                                                  
    end                                                                                                                                                      
                                                                                                                                                             
    -- return to original height                                                                                                                             
    if not goingUp then                                                                                                                                      
      -- ended at top, come back down                                                                                                                        
      for h = 1, height - 1 do                                                                                                                               
        moveBack()                                                                                                                                           
      end                                                                                                                                                    
    end                                                                                                                                                      
                                                                                                                                                             
    -- face depth                                                                                                                                            
    turtle.turnLeft()                                                                                                                                        
                                                                                                                                                             
    if d < depth then                                                                                                                                        
      turtle.dig()                                                                                                                                           
      turtle.forward()                                                                                                                                       
    end                                                                                                                                                      
  end