You can pipe any buttercream into a mold, have you never made buttercream icing for a cake? Tasty experiments!
Just google buttercream icing and have a go at it. Worst case is you have something which you can throw on some brownies or a quick cake hehe.
It's not shelf stable but they are good and creamy.
You can store your bag of buttercream in the fridge but will need to allocate some time for it to "thaw" before piping.
While this isn't our recipe I just grabbed this one off Foodnetwork as an example of the ingredient breakdown, not rocket science--
1 cup unsalted butter
1/2 cup milk, room temperature
1/4 teaspoon salt
2 teaspoons vanilla or other desired flavoring
2 pounds confectioners' sugar