Sponge

term.clear()
term.setCursorPos(1,1)
print("how Long?")
a=tonumber(read())
term.setCursorPos(1,3)
term.clearLine()
print("how Wide?")
b=tonumber(read())
term.setCursorPos(1,5)
term.clearLine()
print("how Deep?")
c=tonumber(read())

right = true

goForward = 6
goSideward = 6
goDown = 6

function move(direction)            --turtle moving
    if direction == "up" then
        while not turtle.up() do
            if not turtle.digUp() then
                turtle.attackUp()
            end
        end
    elseif direction == "down" then
        while not turtle.down() do
            if not turtle.digDown() then
                turtle.attackDown()
            end
        end

    else
        while not turtle.forward() do
            if not turtle.dig() then
                turtle.attack()
            end
        end
    end
end

function row()
    x = 1
    turtle.placeDown()
    turtle.digDown()
    while a-x >= goForward do
        for _=1, goForward do
            move()
            x = x + 1
        end
        turtle.placeDown()
        turtle.digDown()
    end
    if a-x ~= 0 then
        for _=1, a-x do
            move()
            x = x + 1
        end
        turtle.placeDown()
        turtle.digDown()
    end
end

function layer()
    y = 1
    while b-y >= goSideward do
        row()
        if right == true then
            turtle.turnRight()
        else
            turtle.turnLeft()
        end
        for _=1, goSideward do
            move()
            y = y + 1
        end
        if right == true then
            turtle.turnRight()
            right = false
        else
            turtle.turnLeft()
            right = true
        end
    end
    if b-y ~= 0 then
        row()
        if right == true then
            turtle.turnRight()
        else
            turtle.turnLeft()
        end
        for _=1, b-y do
            move()
            y = y + 1
        end
        if right == true then
            turtle.turnRight()
            right = false
        else
            turtle.turnLeft()
            right = true
        end
    end
    row()
end

function cube()
    z = 1
    layer()
    while c-z >= goDown do
        for _=1, goDown do
            move("down")
            z = z + 1
        end
        turtle.turnRight()
        turtle.turnRight()
        layer()
    end
    if c-z ~= 0 then
        for _=1, c-z do
            move("down")
            z = z + 1
        end
        turtle.turnRight()
        turtle.turnRight()
        layer()
    end
end

cube()

term.clear()
term.setCursorPos(1,1)
print("done")