Methods for providing a workpiece computer model including a plurality of objects defined in a body of material. A temporary support frame is provided as part of a two-sided machining process in which the workpiece is partially milled from an obverse side. The machine-control instructions are also based on one or more occupying structures added to the workpiece to fill in one or more excess unoccupied regions of the workpiece that would otherwise be machined away during machining of the objects. Providing such occupying structure(s) reduces the amount of machining that needs to be performed.