https://shop.smartdoll.jp/products/oppai-piggy-bank "They say that Boobs can save the world but what they didn’t say was that Boobs can also save money - introducing the Smart Doll Boob Piggy Bank. Up until now, Piggy Bank's have mostly come in the form of a...pig. When was the last time you felt like giving money to a pig? Research shows that 99.7% of people never end up filling up their piggy banks. But by having the piggy bank in the shape of mankind's hope, one would be more motivated to save - especially for guys. You know when a guy says that the first thing they look at when they see a girl is her face - he is lying through his teeth. This product fits all Smart Dolls girls - currently in Milk color only but soon in Tea and Cocoa. These piggy banks are designed slightly differently from the current busts in a way that they have a base and cap to stop the coins falling out. They come in 3 different sizes - M for 50 yen coins (capacity 10000 yen), L for 100 yen coins (capacity 20000 yen) and XXL for 500 yen coins (capacity 52000 yen). While these products are specifically for Japanese Yen, you can probably use it to work coins from your neck of the woods too."