Wouldn't it be more appropriate that she built it for Marisa? Well... specifically so she can keep Marisa in or out of the forest as well as other annoyances?
How about this: Next time, would you build a giant robot Hisou Tensoku for me?D-don't get the wrong idea! I didn't especially make it for you!Alice! You finally made a giant robot! Congratulations!Is this what tsundere's like?