Can be upgraded, synthesized, purchased, etc. You upgrade. For example, level 4 has a coffee cup, level 6 has a wooden plate, and level 7 has coke bombs and beer bombs. For synthesis, you need a formula and materials. After synthesis, it is valid for 30 days, and you can resmelt it if you have the materials. It's best not to go to the mall to buy, unless you want to buy chocolate cannons or ice eggs. I recommend you go to the Exchange Square to buy them. There are a lot of things to buy there.