> what is there that's not machinable shape-wise, but is still castable
Yes. For example imagine a 3d jewellery made of a web of thin filaments.
It can be non-machinable for two reasons: The wires can be too thin individually and machining them out of a solid block would break them, while they can support themselves once cast. Or you might have shapes where one of the wires is surrounded by the other wires and you can't get the tool in.
Traditionally, hand carve the ring out of wax and use a lost wax casting method. These days you can 3D print in a wax filament or machine the wax in multiple pieces, hand finish, then cast.
Yes. For example imagine a 3d jewellery made of a web of thin filaments. It can be non-machinable for two reasons: The wires can be too thin individually and machining them out of a solid block would break them, while they can support themselves once cast. Or you might have shapes where one of the wires is surrounded by the other wires and you can't get the tool in.
As an example image: https://static.wixstatic.com/media/4f7223_21af8794dc874622a6...