This is going to be a lost PLA pattern for a Pocket Undercutter cast in cooper alloy. Lost PLA is similar to a lost wax casting. Lost PLA uses a PLA pattern rather than a wax pattern. In both Lost PLA and lost wax the patterns are sacrificial in that they are melted out to create the mold cavity. The major advantage of lost PLA and/or lost wax is that positive draft is not needed. More detail can be added to the pattern. For example for the pocket undercutter we could add the tap drill hold and other features.