You can't upgrade your milker. The size of your milk determines on how fast you milk your cow. Then, there are different levels of your milker.
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To upgrade Your Milker you need to milk cows. You can't upgrade it to Copper, Silver, Gold and so forth. But once you get to like level 5 you make around just 2000 dollars a day IN MILK
You can never get a second story house in Harvest Moon DS Cute.
Use the milker in the air in till you have the death sign above your head if you do this every day you will have a level 1 milker in four days (maybe later or sooner) . If you have turbojolt or bodygizer it goes faster because you can heal yourself. That's all !
You can only be a girl in Harvest Moon DS Cute
You cannot get a rabbit in Harvest Moon DS Cute.